Cambridge Prognostic Group (CPG) system for risk stratification of prostate cancer

Cambridge Prognostic Group (CPG) system for risk stratification of prostate cancer

Based on a score from 1 to 5. Calculated using data from:

• Grade Group or Gleason score
• prostate-specific antigen (PSA) level
• tumour stage (TNM staging)

Relationship to Gleason Score and Group

A National Prostate Cancer Audit (NPCA) Report stated (1):

• “… CPG classification can be used to stratify men’s prostate cancer for the NPCA going forward. There will be a noticeable change in the proportion of men in the lowest risk category and thus an impact on the potential ‘over-treatment’ indicator used to monitor the use of radical treatment for these men. However, due to the higher numbers, this indicator will now be more robust, highlighting wider variation among providers than was previously apparent, allowing further improvement to the quality of care…”
• the tool will be used to classify men’s prostate cancer risk in future National Prostate Cancer Audit reporting, replacing the current three-tiered system of low-, intermediate- and high-risk group
• although their demographic characteristics are shown to be similar, there are more men in the lowest risk tier in the new stratification (CPG1) than in the low-risk group and this leads to an overall higher proportion of men identified as potentially ‘over-treated’

A validation study of nearly 75,000 men confirmed that the CPG five-tiered prognostic model had superior discrimination compared to the three-tiered model in predicting prostate cancer death across different age and treatment groups (2)

• identified distinct sub-groups of men within the old intermediate-risk and high-risk criteria who have very different prognostic outcomes

References:

1. NPCA Short Report (February 2021). Using the Cambridge Prognostic Groups for risk stratification of prostate cancer: How could it impact our estimates of potential “over treatment”?
2. Gnanapragasam, V.J., Bratt, O., Muir, K. et al. The Cambridge Prognostic Groups for improved prediction of disease mortality at diagnosis in primary non-metastatic prostate cancer: a validation study. BMC Med 16, 31 (2018). https://doi.org/10.1186/s12916-018-1019-5.