Cancer Registrations Statistics, England 2021- First release, counts only

Cancer registration is the systematic collection of data about cancer and tumour diagnoses. In England, this data collection is managed by the National Disease Registration Service (NDRS) in NHS England. The NDRS collects information on over 300,000 diagnoses of cancer a year, including patient details, as well as detailed data about the type of cancer, how advanced it is and the treatment the patient receives.

Data are submitted to the NDRS from a range of healthcare providers and other services (for example, histopathology and haematology services, radiotherapy departments, screening services and general practitioners). The National Cancer Registration and Analysis Service (NCRAS), which is a part of NDRS, then uses these multiple sources to build a comprehensive picture of cancer incidence in England, as well as other detailed analysis and interpretations covering the entire cancer pathway on all patients in England. For more information, please see the Data Resource Profile for the National Cancer Registration Dataset (NCRD).

The quality and accuracy of the data are validated and processed to ensure that they are consistent and to a high standard. Once all the expected records for any one incidence year have been received and validated, NCRAS takes a snapshot of the dataset, which provides a single, consistent source of cancer registrations. Cancer incidence for 2021 was created from a snapshot taken on 2 September 2023, for the period January to December 2021. The snapshot will vary year on year due to the dynamic nature of registration data:

• new cancer diagnoses will be registered which can include new “late” registrations after cancer incidence has been published for that year
• cancer records can be amended, for example the site code of a record can be modified when more accurate information becomes available
• cancer records can be cancelled (although this is uncommon)
• a less common reason for changes to historical data is a patient exercising their right to opt-out of the cancer registration datasets.

The completeness of the stage at diagnosis data for 2021 diagnoses submitted to NDRS was better than for previous diagnosis years. To speed up registration process, case follow up where the stage at diagnosis was missing, was targeted towards the rarer less well staged sites.

This resulted in a small reduction (2%) in the overall completeness of stage at diagnosis for the 18 common cancers in this publication.

The figures for numbers of “all cancer” in this release refer to all malignant neoplasms which include International Classification of Diseases: ICD-10 codes of C00 to C97, excluding non-melanoma skin cancer (ICD-10 C44).

Although a common cancer, the available figures for NMSC before 2013 are known to be underestimates and unreliable for comparison purposes over time. This is because previously there has been variation in the policies and practices for the recording of NMSC before the establishment of a national cancer registry in 2013. Since 2013, a first NMSC tumour per patient per year methodology has been used which consistently and better reflects the true incidence of NMSC in England.

Any regional differences in benign, uncertain and unknown neoplasms should be interpreted with caution. There is known historical variation in the way these tumours were recorded across the country.

The most recent five years of registered cancer diagnoses may be revised to reflect the results of extra tests that happen while a patient is being treated. Although the estimates of counts for previous years may alter, these changes will be small. After five years have elapsed, it is unusual to see these changes occurring.

The methodology documentation contains important information on:

• the strengths and limitations of the data and how it compares with related data
• uses and users of the data
• how the output was created
• the quality of the output including the accuracy of the data.

Table 5 shows the site definitions used in the estimates of cancer incidence by stage at diagnosis.

Table 5: Cancer site and group definitions by ICD-10 revision 5 code

• Staging systems are often valid for particular combinations of the cancer site and morphologies (subtypes that describe the individual forms and structures of the cancer).
• Some cancers come from a stageable site but have a morphology that means the cancer cannot be staged; these cancers are called “unstageable”.
• Some cancers come from a stageable site and have a morphology that means they could be staged but some other vital information is not available. These cancers are described as having missing data.
• The UK and Ireland Association of Cancer Registries Performance Indicator for early stage includes primary peritoneal carcinomas in the Ovary and Fallopian tube group – these have not been included in this report.

The staging system used is typically TNM. The TNM system puts cancers in a group from 1 to 4 depending on the cancer, or tumour, size (T); which, if any, lymph nodes have cancer cells (N); and if the cancer has spread (metastasised) to other parts of the body (M). Different versions of TNM are used according to the diagnosis year and type of cancer, in line with international guidance.

For some cancers, a site/group-specific staging system is used instead of TNM:

• International Federation of Gynecology and Obstetrics (FIGO) staging for gynaecological (ovary, cervical and uterus) cancers
• Ann Arbor staging for non-Hodgkin lymphomas in adults
• Murphy St Jude staging for non-Hodgkin lymphomas in children
• National Wilms Tumour Study staging for Wilms tumours. The NWTS staging system has stages 1 to 5; diagnoses at stage 5 have been mapped to the stage 3 to 4 group.