Colon to Rectum
Lancet Gastroenterol Hepatol. 2022;7(8):711–23
Proportion and stage distribution of screen-detected and non-screen-detected colorectal cancer in 9 European countries: An international, population-based study
Background: The effects of recently implemented colorectal cancer (CRC) screening programs in Europe on CRC mortality will take several years to be fully known. The authors aimed to analyze the characteristics and parameters of screening programs, proportions of CRCs detected through screening, and stage distribution in screen-detected and non-screen-detected CRCs to provide a timely assessment of the potential effects of screening programs in several European countries.
Methods: They conducted this population-based study in 9 European countries for which data on mode of detection were available (Belgium, Denmark, England, France, Italy, Ireland, the Netherlands, Slovenia, and Spain). Data from 16 population-based cancer registries were included. Patients were included if they were diagnosed with CRC from the year that organized CRC screening programs were implemented in each country until the latest year with available data at the time of analysis, and if their age at diagnosis fell within the age groups targeted by the programs. Data collected included sex, age at diagnosis, date of diagnosis, topography, morphology, clinical and pathological TNM information based on the edition in place at time of diagnosis, and mode of detection (i.e., screen-detected or non-screen-detected). If stage information was not available, patients were not included in stage-specific analyses. The primary outcome was proportion and stage distribution of screen-detected versus non-screen-detected CRCs.
Findings: 228,667 CRC cases were included in the analyses. Proportions of screen-detected cancers varied widely across countries and regions. The highest proportions (40–60%) were found in Slovenia and the Basque Country in Spain, where fecal immunochemical test-based programs were fully rolled out, and participation rates were higher than 50%. A similar proportion of screen-detected cancers was also found for the Netherlands in 2015, where participation was over 70%, even though the program had not yet been fully rolled out to all age groups. In most other countries and regions, proportions of screen-detected cancers were below 30%. Compared with non-screen-detected cancers, screen-detected cancers were much more often found in the distal colon (range, 34.5–51.1% screen-detected vs. 26.4–35.7% non-screen-detected) and less often in the proximal colon (19.5–29.9% screen-detected vs. 24.9–32.8% non-screen-detected) p ≤ 0.02 for each country, more often at stage I (35.7–52.7% screen-detected vs. 13.2–24.9% non-screen-detected), and less often at stage IV (5.8–12.5% screen-detected vs. 22.5–31.9% non-screen-detected) p < 0.0001 for each country.
Interpretation: The proportion of colorectal cancer cases detected by screening varied widely between countries. However, in all countries, screen-detected cancers had a more favorable stage distribution than cancers detected otherwise. There is still much need and scope for improving early detection of cancer across all segments of the colorectum, and particularly in the proximal colon and rectum.