Case-mix adjusted percentage of cancers diagnosed at stages 1 and 2 in England, 2020

In October 2018, the government set out a plan for 75% of all stageable cancers to be diagnosed as an early stage by 2028. The improvement in recording of stage continues to be part of the work programme for the National Disease Registration Service. 

Stage is a measure of how much a cancer has grown and spread, with more advanced stages meaning the cancer is bigger or has spread to other parts of the body (lymphatic spread or metastasis). There are usually fewer treatment options at an advanced stage. National public health interventions, such as screening programmes and information and educational campaigns (for example, Be Clear on Cancer and Help Us Help You), aim to increase the percentage of early diagnoses. 

A cancer is considered stageable if a staging system exists for where the cancer originates in the body (the site) and the type of cells in the cancer. For example, a staging system doesn’t exist for the types of cancer found in the heart. 

The staging system used here 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 
• International Staging System (ISS) for myelomas 
• Binet staging for chronic lymphocytic leukaemia (CLL) 
• Chang staging for Medulloblastoma 

• International Neuroblastoma Risk Group staging system (INRGSS) for neuroblastoma 
• National Wilms Tumour Study staging for Wilms tumours. 

For these cancer sites/groups, TNM stage has been used where the site/group-specific stage was unknown. Cervical cancer is the exception, whereby a cancer is only considered staged if a FIGO staging value is available. These site/group-specific staging systems can be mapped to TNM as follows: 

• Stage 1 = TNM stage 1, FIGO stage 1, Ann Arbor stage 1, NWTS 1 
• Stage 2 = TNM stage 2, FIGO stage 2, Ann Arbor stage 2, NWTS 2 

• Stage 3 = TNM stage 3, FIGO stage 3, Ann Arbor stage 3, NWTS 3 
• Stage 4 = TNM stage 4, FIGO stage 4, Ann Arbor stage 4, NWTS 4-5 

For this publication, cancers that have been staged in an alternate system (Binet; ISS; Chang; INRGSS) and cannot be mapped to TNM, have been included as two separate categories 

• Staged – other early = Binet A-B; ISS 1-2; Chang M0; INRGSS L1-L2 
• Staged – other advanced = Binet C; ISS 3-4; Chang M1-M4; INRGSS M&MS 

Both TNM staging system and site/group-specific staging systems can be mapped to early (referred to as stages 1 & 2) or advanced stage (referred to as stages 3 & 4) as follows: 

• Stages 1 & 2 = Stage 1, Stage 2, Staged – other early 
• Stages 3 & 4 = Stage 3, Stage 4, Staged – other advanced 

In this publication the rare subset of breast cancers known as "Paget's disease of the nipple", which are classified as "stage group 0", have been included with non-malignant tumours where appropriate and do not appear in the malignant cancer statistics presented. There are less than 200 of these tumours diagnosed per year. This rule has also been applied to the small number of occurrences of other cancers with "stage group 0". This may cause a small discrepancy in counts and totals compared to other publications. 

The case-mix adjusted ‘percentage of cancer diagnosed at stages 1 and 2’ indicator makes adjustments for the following patient-level characteristics: age, gender, cancer site and area-level deprivation as defined by the Index of Multiple Deprivation. These adjustments are applied to the characteristics of the baseline population. This is to enable comparisons of changes to ‘percentage of cancers diagnosed at stages 1 and 2’ indicator which are unrelated to changes to the underlying patient characteristics over time. 

Without case-mix adjustment, the unadjusted ‘percentage of cancers diagnosed at stages 1 and 2’ indicator for a sub-ICB will be impacted if: 

• cancers less likely to be diagnosed at stages 1 and 2 occur more frequently in the sub-ICB than the national average, which will make the sub-ICB’s measure look worse than it is 
• cancers more likely to be diagnosed at stages 1 and 2 occur more frequently in the sub-ICB than the national average, which will make the sub-ICB’s measure look better than it is 

For example, breast cancer is more frequently diagnosed at stages 1 and 2 than lung cancer. Therefore, without case-mix adjustment, sub-ICBs with a higher than average occurrence of breast cancer will tend to perform better on the ‘percentage of cancers diagnosed at stages 1 and 2’ indicator, compared to sub-ICBs with a higher than average occurrence of lung cancer. 

The 75% ambition indicator measures the 1-year rolling percentage of all staged malignant cancers diagnosed, excluding non-melanoma skin cancer, that are recorded as presenting at stage 1 or 2, in England in 2013 to 2020. The indicator is not case-mix adjusted and is presented only for Cancer Alliances. 

The cancer sites/groups identified for this indicator are stageable sites/groups that meet 2 criteria: at least 1,500 cancers diagnosed annually in England and an average of at least 70% of cancers having a complete stage over the past 3 years.

Due to the impact of the COVID-19 pandemic on both clinical and data quality arrangements, the ability to obtain stage data for cancer registrations was reduced for the 2019 and 2020 diagnosis years. In 2019, the proportion of stageable cancer diagnoses with a registered stage fell from 85% in 2018 to 76%. For the 2020 diagnosis year, this has increased to 81%.

The sites contributing to the CMA indicator, taking into account staging completeness, will be reviewed for each release. 

Reliability gives an indication of how robust the performance measure is. The possible range lies between 0 and 1, with values closer to 1 indicating higher reliability. Reliability above 0.7 is considered sufficient, with 0.9 considered the threshold for pay-for-performance measures.

Low reliability indicates that variation by chance, due to small numbers, is having an unduly high influence on the performance measure. Lower reliability is likely to reflect smaller sample sizes, due to smaller populations within a sub-ICB or use of annual rather than 3-year summary statistics. 

The two-sided proportions Z-test was used to test whether proportions were different from each other. A p-value of 0.05 was used to determine if the test was statistically significant.