1. Methodology background


Publication

Adult cancer survival in England

Adult cancer survival by stage at diagnosis for England

Cancer survival for children in England

Geographic patterns of cancer survival
National Statistic   Experimental Statistics Experimental Statistics  

Frequency

Annual

Annual

Annual

Annual

How compiled

Administrative
data

Administrative
data

Administrative
data

Administrative
data

Geographic coverage

England

England

England

England, NHS
England Regions, Cancer Alliances and National Cancer Vanguards, and
Sustainability and Transformation Partnerships

Last revised


29 June 2017

29 June 2017

29 June 2017

23 March
2017
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2. Important points

  • Due to methodology changes to the most recent bulletins, this Quality and Methodology Information (QMI) report on cancer survival has been updated in collaboration with Public Health England.

  • The main change to the methodology for calculating cancer survival was to use different weights when age-standardising; the change in weights applies to the calculation of adult and sub-national cancer survival and this update in methodology has been applied to the historic data to enable the use of a consistent back series of data.

  • Our survival estimates are the estimation of the proportion of patients surviving their cancer after one, five or 10 years based on detailed patient and background population survival data; this is not crude survival, which is simply the proportion of patients alive after one, five or 10 years.

  • Due to the need for information on patient follow-up for at least one year after diagnosis, all survival estimates calculated have at least one year latency (the time between first exposure to incidence or death), except for those using the hybrid approach, which include less than one year.

  • 1-year, 5-year and 10-year cancer survival estimates are included in both the Adult cancer survival in England and Cancer survival for children in England releases, while 1-year and 5-year sub-national survival estimates are included in the Geographic patterns of cancer survival release; 1-year survival is presented in the Adult cancer survival by stage at diagnosis for England release.

  • Further sub-national survival estimates are available for Clinical Commissioning Groups and Sustainability and Transformation Partnerships using a different methodology and are therefore not directly comparable.

Notes: Important points
  1. Quality and Methodology Information (QMI) reports replaced Summary Quality Reports (SQR) from April 2011
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3. Overview

Office for National Statistics (ONS) in partnership with Public Health England (PHE) publishes a suite of bulletins on cancer incidence and survival, with accompanying Quality and Methodology Information (QMI) reports for cancer incidence and index of cancer survival. Survival estimates are produced for the most common cancers in adults (aged 15 to 99 years) by stage and diagnosis, and for all cancers combined in children (aged 0 to 14 years).

This report provides details of the methodology used, in partnership between ONS and PHE, to produce the following national and experimental statistics:

  • Adult cancer survival in England (National Statistics)

  • Adult cancer survival by stage at diagnosis for England (Experimental Statistics)

  • Cancer survival for children in England (Experimental Statistics)

This report also covers the methodology applied for the Geographic patterns of cancer survival in England (National Statistics) bulletin, which provides cancer survival estimates for common cancers at a sub-national level, namely NHS England Regions, Cancer Alliances (including the National Cancer Vanguards) and Sustainability and Transformation Partnerships:

Sub-national survival estimates are also available by Clinical Commissioning Group but are produced as an Index of cancer survival. Sustainability and Transformation Partnerships (STPs) are now included in the index of cancer survival bulletin to provide a single measure of cancer survival over time at this geography level. The alternative method is outlined in the Index of cancer survival Quality and Methodology Information report.

This analysis has been prepared jointly (from June 2017) with the National Cancer Registration and Analysis Service (NCRAS) within PHE.

Cancer is a major cause of death, accounting for around one-quarter of deaths in England. More than one in two people will develop cancer at some point in their life1. In July 2015, an Independent Cancer Taskforce published Achieving world-class cancer outcomes: a strategy for England 2015 to 2020, which included the aim to improve survival rates for cancer patients. This report sets out how the government plans to improve cancer outcomes (including improving survival rates through reductions in the proportion of patients who are diagnosed with cancer at an advanced stage), screening and treatment standards. These publications of national survival statistics enable the monitoring of changes in cancer survival over time, to assess progress in achieving these aims.

This report contains the following sections:

  • Output quality

  • About the output

  • How the output is created

  • Validation and quality assurance

  • Concepts and definitions

  • Other information, relating to quality trade-offs and user needs

  • Sources for further information and advice

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4. Output quality

This report describes the quality of the output and details the points that should be noted when using the output.

We have developed Guidelines for measuring statistical quality; these are based upon the five European Statistical System (ESS) quality dimensions. This report addresses these quality dimensions and other important quality characteristics, which are:

  • relevance

  • timeliness and punctuality

  • coherence and comparability

  • accuracy

  • output-quality trade-offs

  • assessment of user needs and perceptions

  • accessibility and clarity

More information is provided about these quality dimensions in the following sections.

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5. About the output

The national adult cancer survival publications present 1-year, 5-year and 10-year age-standardised net cancer survival for tumours diagnosed in England during a five-year period followed up for at least one whole calendar year, for the 25 most common cancers.

The survival by stage publications present 1-year age-standardised net cancer survival for tumours diagnosed in England during a calendar year and followed up for at least one whole calendar year, with an estimate of survival from nine common cancers separately. These common cancers are:

  • bladder

  • breast (women only)

  • colorectal

  • kidney

  • lung

  • melanoma

  • ovary

  • prostate

  • uterus

The national childhood cancer survival series presents 5-year and 10-year overall survival for tumours diagnosed in England from 1990 onwards, and followed up to the end of the most recently completed calendar year for all cancers diagnosed.

The geographic patterns of cancer survival series presents 1-year and 5-year age-standardised net cancer survival for tumours diagnosed during a five-year period followed up for at least one whole calendar year for 14 common cancer sites. Survival estimates are published for England, NHS England Regions, Cancer Alliances and National Cancer Vanguards, and Sustainability and Transformation Partnerships (STP).

The analyses in the national bulletins present age-standardised and age-specific results for:

  • 1-year net cancer survival calculated using a cohort approach for the adult survival estimates of cancer survival in England, and cancer survival by stage in England

  • 1-year overall cancer survival for childhood cancer in England

  • 5-year net cancer survival calculated using a complete approach for adult survival in England

  • 5-year overall cancer survival calculated for childhood cancer in England, using a cohort approach for diagnoses that can be followed up for at least five calendar years and a period approach for more recent diagnoses

  • 5-year overall cancer survival calculated using a hybrid approach for childhood cancer in England

  • 10-year net cancer survival calculated using a hybrid approach for adult survival in England

  • 10-year overall cancer survival calculated using a hybrid approach for childhood cancer in England

The sub-national analysis for NHS Regions, Cancer Alliances and Sustainability and Transformation Partnerships includes:

  • 1-year net age-standardised cancer survival calculated using a cohort approach over a five-year period

  • 1-year net un-standardised cancer survival calculated using a cohort approach over an eight-year period with a measure of annual change

  • 5-year net age-standardised cancer survival calculated using a complete approach over five combined years

  • 5-year net un-standardised cancer survival calculated using a complete approach over an eight-year period with a measure of annual change

Relevance

(The degree to which the statistical outputs meet users’ needs.)

Users of cancer survival estimates include government organisations, health policy-makers, cancer charities, academics and researchers, cancer registries, the general public, and the media. Population-based cancer survival statistics are used to:

  • plan services aimed at cancer prevention and treatment

  • feed into national cancer plans – the Department of Health identified cancer as a specific improvement area for preventing people dying prematurely, given that a significant gap remains in survival compared with the European average; the Independent Cancer Task Force set out six strategic priorities to help improve cancer survival in England, including reducing Clinical Commissioning Group (CCG) variation and the ambition to increase 1-year survival to 75% by 2020 for all cancers combined

  • inform the NHS Outcomes Framework, which was established to monitor overall changes in performance of the NHS and the quality of health outcomes, and includes 1-year and 5-year net survival from colorectal, breast and lung cancers; the NHS Five Year Forward View set out: “that improvements in outcomes will require action on three fronts: better preventions, swifter access to diagnosis, and better treatment and care for all those diagnosed with cancer”

  • provide reliable and accessible information about cancer outcomes to a wide range of groups, including patients and health professionals via health awareness campaigns, cancer information leaflets and websites

  • inform cancer research

Cancer survival is generally influenced by stage at diagnosis, treatment quality and patient factors (for example, frailty or comorbidity). Therefore, there has been an increasing interest in cancer survival by the tumour stage at time of diagnosis for a number of years. This was reflected in an Office for National Statistics (ONS) cancer output consultation in 2012. With improvements in the collection of stage data for cancer registrations by Public Health England (PHE) over the last few years, it is now possible to provide cancer survival estimates by stage at diagnosis for the most common stageable tumour sites.

The adult cancer survival by stage at diagnosis analysis is used by the National Awareness and Early Diagnosis Initiative (NAEDI), which aims to improve cancer survival by earlier diagnosis. The data can help show the improvement in survival that could be made if more cancers were diagnosed earlier. They also show the pattern of survival and stage, which may help show where most improvement can be made. For the most commonly occurring stageable tumour sites, which are also included in the Public Health Outcomes Framework (PHOF) experimental indicator 2.19 (Cancer diagnosed at an early stage). We have excluded non-Hodgkin lymphoma from the PHOF list of stageable tumour sites in the analysis because survival from non-Hodgkin lymphoma varies substantially between patients with the same stage, depending on tumour morphology.

The cancer survival for children in England series is used in the NHS Outcomes Framework, specifically, the 5-year survival from all cancers diagnosed in patients aged 0 to 14 years is used to evidence improvement in preventing people from dying prematurely.

The analyses of survival by stage in adults and survival in childhood have been released as experimental for the time-being, to allow us to gather views and opinions on the analysis undertaken.

The geographic patterns of cancer survival series is used in the indicators set for the Compendium of population health indicators. The compendium includes 1-year and 5-year survival from bladder, breast, cervical, colorectal, lung, oesophagus, prostate and stomach cancers.

Changes in the coding of cancer occur when a new version of the International Statistical Classification of Diseases (ICD) is implemented. Currently, all malignancies are coded using ICD volume 10 (ICD-10), which replaced ICD-9 in 1995. Coding cancers with the most recent version of the ICD means that coding represents an accurate and up-to-date picture of cancer, so that cancer-related outputs continue to meet users’ needs.

Timeliness and punctuality

(Timeliness refers to the lapse of time between publication and the period to which the data refer. Punctuality refers to the gap between planned and actual publication dates.)

Historically, cancer registries in England were obliged by the Department of Health to provide data on all new cancer diagnoses to ONS within 18 months of the end of the calendar year. However, with the single National Cancer Registration and Analysis Service (NCRAS) for England within PHE and the collaboration with ONS, the data are cleaned in-house within NCRAS and quality assured by colleagues in ONS. The process of data ascertainment and linkage of cancer registrations to death registrations is also substantially reduced due to this ONS and PHE collaboration. PHE’s cancer survival team are therefore able to produce cancer survival estimates in a shorter time frame than before (that is, we will be publishing three sets of national results in June 2017 at the same instance, compared with September for adults and February for childhood for previous years).

Since the registration of 2012 cancer diagnoses onwards, the use of the same data collection tools and methodologies across England has enabled a consistent approach to collecting and recording cancer staging data. This new approach successfully led to more than 60% of all stageable tumours being staged for the first time in 2012. For 2013, 2014 and 2015 diagnoses, the proportion staged has further improved to 71%, 77% and 80% respectively.

For more details on related releases, the GOV.UK release calendar provides up to 12 months’ advance notice of release dates. If there are any changes to the pre-announced release schedule, public attention will be drawn to the change and the reasons for the change will be explained fully at the same time, as set out in the Code of Practice for Official Statistics.

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6. How the output is created

General principles of the methodology for this output

The estimates produced in this publication have been produced by the National Cancer Registration and Analysis Service (NCRAS) of Public Health England (PHE). These national and experimental statistics implement the United Kingdom and Ireland Association of Cancer Registries' ratified Standard Operating Procedure Guidelines on Population Based Cancer Survival Analysis.

Survival estimates are age-standardised wherever possible, to improve the comparability between population groups and over time. This is because net survival varies with age at diagnosis and the age profile of cancer patients can vary over time and between geographical areas.

From June 2017, age-standardised estimates for adults have been calculated using the International Cancer Survival Standard (ICSS) age-weightings. The impact of the change to methods of adopting the ICSS international cancer patient population for age standardising survival ratios is detailed in the Impact of updating cancer survival methodologies for national estimates and paper. In summary, the benefits are:

For childhood cancer, the estimates are age-standardised by giving equal weight to all three age-groups (0 to 4 years, 5 to 9 years and 10 to 14 years).

Un-standardised survival estimates for each year of an eight-year period are presented in the datasets. The annual trend in survival is the slope estimated by variance-weighted least-squares regression of the annual survival estimates. This represents the average annual change in net survival over eight consecutive years. Due to the year-on-year variability of the survival estimates in smaller areas (for example, Sustainability and Transformation Partnerships), the average annual trend may be increasing over eight years, even though a drop in survival may be observed between two consecutive years.

The annual trend in survival is only reported if at least three annual survival estimates were available and the absolute difference in survival between two consecutive years did not exceed 20%. The p-value indicates whether the average annual change in survival is statistically significant. A p-value lower than 0.05 indicates that we can be more than 95% confident that the trend represents a real change and did not just occur by chance.

From February 2017, the Geographic patterns of cancer survival release uses the complete approach to estimate survival rather than the cohort approach that was previously used. There was also a change from combining three years of diagnosis data to combining five years of data. This change allowed for more cancer sites to be included in the analysis; fewer estimates were suppressed due to more diagnoses being included.

Survival methodology

The adults’ survival analyses, overall and by stage or geography level, use the Pohar-Perme net survival estimator, as implemented by Isabelle Clerc-Urmès, Michel Grzebyk and Guy Hédelin’s stns programme in Stata. Net survival accounts for the so-called “informative censoring” bias, that is, the fact that some groups of patients are less likely to be followed up for at least five years than others, independently of their cancer prognosis. Net survival is estimated with an excess hazard model in which the all-cause mortality is modelled as the sum of the excess (cancer-related) mortality hazard and the expected (or background) mortality.

Background mortality is derived from population life tables. The life tables used are supplied by the London School of Hygiene and Tropical Medicine’s Cancer Survival Group. English life tables for 2011 are used for 2011 to 2015. In these life tables, the mortality of cancer patients is compared with that of individuals in the general population who belong to the same single year of age (0 to 99 years), sex, population weighted quintile of the index of multiple deprivation (IMD) and region. Patients are included if they were diagnosed with their tumour when they were between the ages of 15 and 99 years.

For childhood cancer, overall survival is calculated rather than net survival (that is, without adjustment for background mortality), because deaths within five years of a cancer diagnosis are almost always due to the cancer. Overall survival is implemented using the Kaplan-Meier method, as this adjusts particularly well for instances where a patient withdraws from the cohort due to being lost to follow-up (for any reason) but is known to be alive at an earlier time. Patients are included if they were diagnosed with their tumour when they were between the ages of 0 and 14 years.

Inclusions and exclusions criteria

The following criteria are used to identify the patients that are eligible to be included in the analysis (and provided in the inclusion table included as part of the publication release):

  • patients should have a unique identifier

  • patients should have a complete date of birth and be aged between 15 and 99 years at diagnosis for adults and be aged between 0 and 14 years at diagnosis for children

  • patients who have died should have a complete registered date of death

  • patients should have a complete date of cancer diagnosis

  • patients should have a known sex

  • patients should have a known date of being recorded as alive or dead

  • patients should be resident in England and have a valid postcode for usual place of residence

  • tumours should be malignant, newly diagnosed in the studied cohort and a primary tumour

  • cancers of the blood (lymphomas, leukaemia and myelomas) should not occur in a solid tumour

  • patients are included even if they have further new cancer diagnoses later in the period of interest; for each patient, survival time is counted from the earliest diagnosis in each period of interest

  • patients are excluded if they have had a primary tumour of the same site diagnosed before the period of interest

  • patients are included even if they have a primary tumour of another site diagnosed at any time; for each site, patients are included in survival analyses where the earliest diagnosis of a tumour from that site occurred within the period of interest

  • tumours should not be Death Certificate Only (DCO) registrations, where the only confirmed record of the tumour is recorded on the death certificate

  • the sequence of dates should be valid (for example, a patient should not be diagnosed before they are born)

Other decisions applied include:

  • where a patient dies on the date of diagnosis but is not a DCO registration, then these patients should be included in the survival analyses but should have one day added to the recorded date of death to accommodate limits in Stata’s stset command

  • when two or more tumours of the same type are diagnosed on the same day for a patient, the one with the worst prognosis is chosen for inclusion

  • coding the cancers with reference to the International Statistical Classification of Diseases 10th Revision (ICD-10); the details of the coding applied are included in each bulletin

In the overall adult survival analyses, for age groups where the estimates do not meet the following quality criteria, the result is suppressed for that particular age group of the specific cancer site:

  • a minimum of 10 patients should be alive at the beginning of the survival period being estimated

  • at least two deaths registered in the years before or after the duration(s) being estimated

  • the level of the survival estimates should not increase with duration (for example, the survival estimated at five years following diagnosis should be lower than the survival estimated at one year following diagnosis)

  • the standard error of the survival estimates should be lower than 20%

Structured Query Language (SQL) is used to extract data from NCRAS’s Cancer Analysis System and Stata code is used for preparing the data and calculating these estimates. To aid transparency and allow replication of the estimates produced in this bulletin, annotated copies of the SQL and Stata code can be provided on request. Please email any requests to NCRASenquiries@phe.gov.uk.

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7. Validation and quality assurance

Accuracy

(The degree of closeness between an estimate and the true value.)

Cancer survival releases are produced using the most robust methods available for population-based cancer survival estimation. All bulletins published on cancer survival use the same underlying data files, which are prepared for analysis by using the same documented quality assurance procedures.

Each year, almost 300,000 patients are newly diagnosed with cancer in England. Public Health England’s (PHE’s) National Cancer Registration and Analysis Service (NCRAS) records new cancer registrations covering the entire population of England and holds cancer registration data from the former regional cancer registries, who had registered tumour data since the 1960s.

Previously, data from Office for National Statistics (ONS) historic cancer registrations were used, but it has now been agreed that data provided by PHE will act as the only sources of cancer registrations for England and ONS will archive its registry.

NHS Digital routinely updates these individual cancer records with information on each patient’s vital status (alive, emigrated, dead or not traced). Typically, at the time that data are extracted for the most recent statistical bulletins, less than 0.3% of patients diagnosed cannot be traced during the relevant period.

Cancer incidence data for England are collected by the regional offices of NCRAS, which is part of PHE. Data are submitted to the NCRAS from a range of healthcare providers and other services (for example, pathology laboratories). The quality and accuracy of the data submitted by different sources may vary. The regional offices of NCRAS collate all the data for each patient, including checks for internal consistency of the sequence of dates, as well as the cancer site, sex, morphology and duplicate registrations. These checks are closely based on those published by the International Agency for Research on Cancer (IARC) and are reported on by the UK and Ireland Association of Cancer Registrations (UKIACR) series of performance indicators.

If a record fails any critical validation check – for example, if the date of birth is invalid – the records are not reported in Cancer Registration Statistics, nor in any other ONS publication, including survival releases, since it is not possible to send these records for verification of the patient’s vital status to NHS Digital. If a record passes all critical validation checks, or fails one or more minor quality controls, these records are sent to NHS Digital for verification of vital status.

Further checks are required for survival analysis; these are carried out in two stages. The first stage involves checking the eligibility of a record based on its completeness, the patient’s usual residence, tumour behaviour and morphology. Patients with an invasive, primary, malignant tumour are eligible for analysis (see “How the output was created” section, which lists the full criteria). Ineligible patients include those whose tumour is benign (not malignant) or “in situ” (malignant, but not invasive) or of uncertain behaviour, or for which the organ of origin is unknown.

The second stage involves checking the patient’s age (15 to 99 years for adults; 0 to 14 years for children), vital status, that the patient’s sex is compatible with the cancer site, the dates are valid, and the patients’ tumour was not registered solely from a death certificate.

Since 2001, cancer registrations for each year have been estimated to be between 96% and 99% complete at the time of extraction, with completeness improving over time. However, it is important to note that the cancer registration database is dynamic.

In common with cancer registries in other countries, cancer incidence in England can take up to five years after the end of a given calendar year to reach 100% completeness and stability, because of late registrations, corrections and deletions. The estimate of completeness for a diagnosis year is based on the figures published for the three previous years, compared with the number of late registrations subsequently received for these years. It is therefore the difference between the figures published in Cancer registration statistics (and all subsequent ONS cancer incidence publications within that reporting year) and late registrations received after the publication date cut-off. It is not an estimate of the number of cancers that are never recorded.

It is important to note that the checks and quality measures undertaken in the PHE National Cancer Registration and Analysis Service are similar to the checks that the ONS Cancer Registry historically applied to the National Cancer Registration database.

Coherence and comparability

(Coherence is the degree to which data that are derived from different sources or methods, but refer to the same topic, are similar. Comparability is the degree to which data can be compared over time and domain, for example, geographic level.)

International comparisons of cancer survival figures are occasionally reported. Care should be taken when interpreting results from different countries, because of known differences in healthcare and cancer registration systems, which are likely to affect results. A discussion of the issues raised by comparison of survival figures from different countries was published as part of the International Cancer Benchmarking Partnership (ICBP) study. Other international sources of survival by stage statistics include those published by National Cancer Institute in the US and the Canadian Cancer Society.

Care should be taken when comparing the single diagnosis year “all stage” estimate in the cancer survival by stage bulletin with those previously published as part of the geographic patterns of cancer survival in England for 1-year site specific cancer survival estimates, as there can be differences. This is caused almost entirely by differences in the age-standardisation weights, for example, PHE use the International Cancer Survival Standard (ICSS) weights while the weights from Coleman et al (1999)2 were used in the previous production of the National Statistics.

The issue of comparability of cancer survival statistics across the UK has been discussed at the UKIACR Executive Board and a consensus has been made to use the ICSS weights in cancer survival analysis in England, Scotland, Wales, Northern Ireland and the Republic of Ireland (as well as the same exclusions in data) so that results can be comparable across all countries in the UK and Ireland.

Estimates for England and Sustainability and Transformation Partnerships (STPs) are published in both the Index of cancer survival by Clinical Commissioning Groups in England bulletin and the Geographic patterns of cancer survival in England bulletin. Care should be taken when comparing these estimates for one-year and five-year site-specific cancer survival estimates as there can be differences. The specific cancer sites presented in both publications are breast (women) and lung, with colorectal (C18 to C20) being included in the cancer survival index whilst cancer of the colorectum (C18 to C20 and C21.8) is presented in the survival estimates. There are also different methodologies applied to calculate net survival and the cancer survival index. Further details of the other methodology can be found in the Cancer survival statistical bulletins Quality and Methodology Information report.

Cancer survival estimates are published at England level by various organisations and they will not all be directly comparable. Raw data may be taken from different sources and differences in quality assurance procedures will influence final estimates.

Cancer Research UK publishes relative cancer survival estimates by geography, deprivation level, cancer site, age at diagnosis and sex.

The Northern Ireland, Scottish and Welsh registries publish national figures for their respective countries. The period for which most recent data are available may differ between countries.

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8. Concepts and definitions

(Concepts and definitions describe the legislation governing the output, and a description of the classifications used in the output.)

Definitions

Cancer

For adults, cancers are coded using the International Statistical Classification of Diseases 10th Revision (ICD-10). ICD-10 coding for cancer is based on the nature and anatomical site of the cancer. ICD-10 replaced the previous revision, ICD-9, in 1995.

For the purposes of adult cancer registration, the term “cancer” includes all neoplasms that are both invasive and malignant (tumours that invade into surrounding tissues), which are conditions listed under site code numbers C00 to C97 in ICD-10. In addition, all “in situ” (malignant but not invasive) neoplasms (D00 to D09), certain benign (not malignant) neoplasms (D32 to D33, D35.2 to D35.4), and neoplasms of uncertain or unknown behaviour (uncertain whether benign or malignant, D37 to D48) are registered.

Morphology and behaviour codes used can be found in the International Classification of Diseases for Oncology, Second Edition (ICD-O-2).

Childhood cancer registrations include all children (aged 0 to 14 years) diagnosed with a primary malignant neoplasm of any organ, or a non-malignant neoplasm of the brain and central nervous system (CNS). Cancers of the skin, other than melanoma, and secondary and unspecified malignant neoplasms, are excluded. Children whose tumour was only reported on a death certificate (which represent 0.5% of all childhood tumours) are also excluded, because their duration of survival is unknown. Inclusion in the childhood cancer survival analysis is defined in the third edition of the International Classification of Childhood Cancer and further details of the eligibility and exclusion criteria have been published in Control of data quality for population-based cancer survival analysis.

Primary cancer

A primary cancer is the tumour that first develops in an identifiable part of the body, for example, the stomach, and usually gives the name to the type of cancer with which a patient is diagnosed.

Metastatic or secondary cancer

A metastatic or secondary cancer is a cancer that has spread from the first primary cancer, which may be located within the same site as the first primary cancer (local metastasis) or spread beyond the site of the first primary cancer (distant metastasis). The metastatic cancer should have the same underlying cell biology and morphology as the first primary cancer. A spread of primary tumour cells within the system of lymph nodes is not usually considered to be metastases of the primary tumour.

Cancer stages

Cancer stage at diagnosis is a measure of how far the primary tumour has grown when the patient first presents in hospital. It is measured and recorded according to internationally agreed standards. The most common staging standards3 are agreed by the Union for International Cancer Control (sometimes called the TNM staging method) and are based on three components: tumour size (the T component), nodal involvement of the lymphatic system (N) and metastatic spread (M). Some gynaecological cancers are staged using an alternative method set out by the International Federation of Gynaecology and Obstetrics (FIGO). For cancers of the ovary and the uterus, FIGO stages can be uniquely matched to TNM stages and this has been used to supplement the TNM staging data.

Although the combinations of tumour size, nodal involvement and metastatic spread change by tumour type, generally there are four stages of cancer progression:

  • stage 1: the primary tumour is usually small and is contained within the body organ in which the tumour started growing

  • stage 2: although larger, the primary tumour has not spread to other parts of the body; spread to the lymphatic system may be included depending on the primary tumour site

  • stage 3: the primary tumour is larger and may have spread into neighbouring parts of the body and into the lymphatic system

  • stage 4: the primary tumour has spread to at least one other part of the body, creating a secondary or metastatic tumour

There are several reasons why a tumour cannot be staged, for example, some samples taken do not produce clear results and some patients are too unwell to undergo the surgery required to obtain a tissue sample for staging. If the tumour size, nodal involvement or metastatic involvement is not recorded for a particular tumour, then it may not be possible to derive an overall stage at diagnosis. In this analysis, missing stage is treated as a separate category and survival estimates are produced for patients with “missing stage at diagnosis” alongside the other categories of known stage.

Health geographies

NHS England Region

NHS England Regions cover healthcare commissioning and delivery in their area and provide professional leadership on finance, nursing, medical, specialised commissioning, patients and information, human resources, organisational development, assurance and delivery. Regional teams work closely with organisations such as Clinical Commissioning Groups (CCGs), local authorities, health and wellbeing boards as well as General Practitioner (GP) practices.

Cancer Alliance

Cancer Alliances are a way to bring together local senior clinical and managerial leaders representing the whole cancer patient pathway across a specific geography. Together with the National Cancer Vanguard, they will lead the local delivery of the Independent Cancer Taskforce’s ambitions for improving services, care and outcomes for everyone with cancer.

Sustainability and Transformation Partnership (STP)

The NHS and local councils have come together in 44 areas covering all of England to develop proposals to improve health and care. They have formed new partnerships – known as Sustainability and Transformation Partnerships – to plan jointly for the next few years. They are built around the needs of the local population across whole areas, not just those of the individual organisations involved.

Survival methods

Overall survival

This is the cumulative probability of all-cause survival. Overall survival is estimated for childhood cancers, where this is considered a reliable estimator of the cancer survival because the death of a child within five years of diagnosis is almost always due to the cancer.

Kaplan-Meier

A method of non-parametric survival analysis that adjusts particularly well for right censoring, which occurs if a patient withdraws from the cohort due to being lost to follow-up (for any reason) but is known to be alive at the last point of known follow-up. This method is used to produce or obtain the childhood cancer survival estimates.

Net survival

The survival of cancer patients compared with the background mortality that patients would have experienced if they had not had cancer. The Pohar-Perme estimator of net survival is an unbiased estimator that accounts for “informative censoring” bias. “Informative censoring” refers to the fact that some groups of patients are less likely to be observed for the full duration of follow-up than others, independently of their cancer prognosis.

Relative survival

An estimate of the probability of survival from the cancer alone excluding other potential causes of death.

Survival analysis approaches

The following survival approach diagrams highlight the diagnosis year for the demonstrated approach and the patient years of follow-up included in that approach. A patient pathway begins with diagnosis in year zero when there are no years of follow-up, this continues right across the diagram increasing for each year of follow-up. For example, patients diagnosed in 2008 with follow-up until 2015 have at least seven years of follow-up. These diagrams focus on 5-year survival but the principles are also applicable to 10-year survival.

Cohort approach

When follow-up information is available for each patient for at least one year, 1-year survival can be estimated using the classical cohort approach. For example, once follow-up information is available for each patient over the entire calendar year following their diagnosis, the cohort approach can be used to estimate 1-year survival by combining the conditional probabilities of survival to the end of each successive sub-period of the analysis.

Figure 1 highlights 5-year survival using the cohort approach. This approach requires that at least five complete years of potential follow-up are available for each patient considered. It’s the simplest approach as all patients could be diagnosed in the same year and potentially followed up for the same length of time. However, it could also be used for patients diagnosed in different years, for example, to calculate survival for patients diagnosed in 2008 to 2010; as long as all patients have full follow-up available for the latest year. The restriction with this approach is that it has implicit latency and cannot be calculated until at least five years have passed.

Complete approach

The complete approach to survival analysis, a variant of the classical cohort approach, is used when some patients may have been followed up for less than the full period. For example, it is viable to use the complete approach to produce estimates for patients diagnosed during 2010 to 2014 with follow-up until 31 December 2015, even though not every patient has had the opportunity to be followed up for the full five years. In this example, the potential follow-up time varies between a single year and five years, depending on the year of diagnosis.

The complete approach for 5-year survival is highlighted in Figure 2. This approach uses all potential years of follow-up for patients diagnosed in a five-year period. The advantage to this approach is it combines timeliness and efficiency using all of the available follow-up. However, this approach cannot be used to give an estimate for a single diagnosis year.

Period approach

A period estimate of 5-year survival is a short-term prediction of survival for patients diagnosed in that period, on the assumption that they will experience the most recently observed conditional probabilities of survival in each year up to five years since diagnosis.

Figure 3 shows that for each year of potential follow-up included they were from patients diagnosed in different years. In this example, patients diagnosed in 2014 potentially have one year of follow-up, then patients diagnosed in 2013 potentially have two years of follow-up given that they survived the first year. This is then true for each successive year until patients diagnosed in 2010 are potentially followed up for the fifth year given they survived the fourth year.

Hybrid approach

The hybrid approach, a variant of the period approach, is used for short-term predictions when the follow-up data are more recent than the incidence data. This short-term delay arises from the quality assurance processes applied in registering a cancer diagnosis. These estimates assume that the probability of survival from the patients included would remain stable for the following five years. Since survival is in fact improving over time, the hybrid estimate of survival will be lower than that which we can expect to observe five years from now, when the full cohort-wise estimates will be available. However, it has the advantage of being available several years sooner.

Figure 4 highlights five-year survival using the hybrid approach. It is similar to the period approach but the first year of survival based on patients with follow-up from the year before. This is because typically registries only have registrations data up to one year behind potential follow-up. This method uses the cohort approach for the first year of follow-up for patients diagnosed in 2014, then uses the period approach for the remaining four years of potential follow-up for patients diagnosed between 2010 and 2013.

The hybrid approach can be used to predict estimates of 10-year survival, assuming that the conditional probabilities of surviving for patients diagnosed in current year are equal to those diagnosed over the full 10-year period of available data.

More information on the differences between survival approaches can be found in the article estimating and modelling relative survival.

Key words used in cancer survival

Age-standardisation

A technique used to enable metrics derived for different populations to be robustly compared even when the populations are different in terms of their age profiles. Age-standardised rates also allow for more robust comparisons between males and females, years, and geographical areas.

95% confidence interval

A measure of the uncertainty around an estimate. Confidence intervals provide a range of values that are likely to contain the underlying population parameter with a given level of certainty. If the underlying rate of cancer survival remained the same and 100 cohorts were sampled over time and 95% confidence intervals were constructed for each of these cohorts, then 95 of the confidence intervals are expected to contain that underlying rate.

Follow-up

A measure of the patient’s time at risk. For example, the time from when a patient is diagnosed with cancer, until their date of death or embarkation (out of the NHS system).

Legislation

The Statistics and Registration Service Act 2007 permits the Registrar General to provide to the UK Statistics Authority, to carry out any of its functions, both information that is kept under the Births and Deaths Registration Act 1953 and any other information received by the Registrar General in relation to any birth or death.

The Health Service (Control of Patient Information) Regulations 2002 Statutory Instrument No. 1438, Regulation 2, permits confidential patient information relating to patients referred for the diagnosis or treatment of cancer to be processed for the following purposes:

  • the surveillance and analysis of health and disease

  • the monitoring and audit of health and health-related care provision and outcomes where such provision has been made

  • the planning and administration of the provision made for health and health-related care

  • medical research approved by research ethics committees for the provision of information about individuals who have suffered from a particular disease or condition where: that information supports an analysis of the risk of developing that disease or condition, and it is required for the counselling and support of a person who is concerned about the risk of developing that disease or condition

This regulation was made under Section 60 of the Health and Social Care Act 2001 and continues to have effect under Section 251 of the NHS Act 2006.

Office for National Statistics (ONS) processes and stores cancer registration data in accordance with the requirements of:

  • the Data Protection Act 1998

  • the Code of Practice for Official Statistics

  • the International Association of Cancer Registries (IACR) and their Guidelines on Confidentiality in Cancer Registries (1992)4

  • the European Network of Cancer Registries (ENCR) Guidelines on Confidentiality (2002)

  • the United Kingdom Association of Cancer Registries (UKACR) Guidelines on Confidentiality 2012

  • the NHS Act 2006

  • the Statistics and Registration Service Act 2007

Public Health England (PHE) processes and stores cancer registration data in accordance with the requirements of:

  • the Data Protection Act 1998

  • the Health Service (Control of Patient Information) Regulations 2002

  • the Caldicott Report 1997

  • Information: To share or not to share? The Information Governance Review March 2013

  • the Freedom of Information Act 2000

  • Section 251 of the NHS Act 2006 (originally enacted under Section 60 of the Health and Social Care Act 2001)

  • Confidentiality: NHS Code of Practice 2003

  • NHS Records Management Code of Practice (Part 1, 2006 and Part 2, 2009)

  • Health and Social Care Act 2012

  • the NHS Information Security Management Code of Practice 2007

  • the Computer Misuse Act 1990

  • the Human Rights Act 1998

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9. Other information

Assessment of user needs and perceptions

(The processes for finding out about uses and users, and their views on the statistical products.)

A stakeholder review of all our cancer publications was conducted in 2010. Stakeholders were asked for their views about how they use the relevant outputs, their importance and their quality. Comments were also sought on any changes respondents would like to see in terms of content and presentation of the outputs and of our cancer web pages. The results of this consultation are available.

A stakeholder consultation of all our cancer publications was undertaken in 2012 to determine future user needs. The results of this consultation are available. One of the important needs identified as part of this consultation was for data on stage at cancer diagnosis, which are collected under the National Cancer Registration Scheme and collated by Public Health England (PHE).

Due to improvements made by PHE in the collection of stage information as part of cancer registration, PHE in partnership with Office for National Statistics (ONS) are now able to publish estimates of survival by stage diagnosis of cancer in the form of Experimental Statistics. ONS will continue working with PHE to ensure that such survival estimates will be published as National Statistics in the future.

To promote ongoing feedback and to accommodate users’ needs, a workshop was held on 20 March 2017, to discuss what aspects they felt would be more useful and what they would like to see in future releases. The workshop included participants from the Department of Health, NHS Digital, Public Health England, Office for National Statistics, Cancer Research UK, Macmillan, Cancer Vanguard and UCL Great Ormond Street Institute of Child Health.

We welcome feedback from users on the content, format and relevance of our statistics. Please contact us via email at cancer.newport@ons.gsi.gov.uk.

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10. Sources for further information or advice

Accessibility and clarity

(Accessibility is the ease with which users are able to access the data, also reflecting the format in which the data are available and the availability of supporting information. Clarity refers to the quality and sufficiency of the release details, illustrations and accompanying advice.)

For information regarding conditions of access to outputs, please refer to:

In addition to this Quality and Methodology Information report, quality information relevant to each release is available in the Quality and methodology section of each of the statistical bulletins and in the metadata contained within the downloadable tables.

All cancer survival statistical bulletins are web-only releases, available in either HTML or PDF formats; data tables are available in Excel format. For further information about cancer survival bulletins, please contact the Cancer Analysis Team via email at cancer.newport@ons.gov.uk or by telephone on +44 (0)1633 456508.

Useful links

More information about cancer survival and registration is available via the UK and Ireland Association of Cancer Registries and the National Cancer Registration and Analysis Service.

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11. References

  1. Ahmad AS, Ormiston-Smith N, Sasieni PD (2015), ‘Trends in the lifetime risk of developing cancer in Great Britain: comparison of risk for those born from 1930 to 1960’, British Journal of Cancer, Volume 112, pages 943 to 947

  2. Coleman MP, Babb P, Damiecki P, Grosclaude PC, Honjo S, Jones J and others (1999), ‘Cancer survival trends in England and Wales 1971 to 1995: deprivation and NHS region’, Studies on Medical and Population Subjects, Number 61, London: The Stationery Office, pages 55 to 106

  3. Sobin LH, Gospodarowicz MK and Wittekind C (2009), ‘TNM Classification of Malignant Tumours’, Seventh Edition, Wiley-Blackwell

  4. Coleman MP, Muir CS, Ménégoz F (1992), ‘Confidentiality in the cancer registry’, British Journal of Cancer, Volume 66, pages 1,138 to 1,149

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