Screen-Detected Colorectal Cancers Have a More Favourable Stage Distribution than Colorectal Cancers Detected Otherwise

In a population-based study conducted in 9 European countries for which data on mode of detection were available (Belgium, Denmark, England, France, Italy, Ireland, the Netherlands, Slovenia, and Spain), the proportion of colorectal cancer cases detected by screening varied widely between countries. However, in all countries, screen-detected cancers had a more favourable stage distribution than cancers detected otherwise. The findings are published by Prof. Hermann Brenner of the Division of Clinical Epidemiology and Aging Research, German Cancer Research Center in Heidelberg, Germany and colleagues on 10 May 2022 in The Lancet Gastroenterology & Hepatology.

The authors wrote in the study background that the effects of recently implemented screening programmes for colorectal cancer in Europe on colorectal cancer mortality will take several years to be fully understood. The study team aimed to analyse the characteristics and parameters of screening programmes, proportions of colorectal cancers detected through screening, and stage distribution in screen-detected and non-screen-detected colorectal cancers to provide a timely assessment of the potential effects of screening programmes in several European countries. They conducted a population-based study with data from 16 population-based cancer registries.

Patients were included if they were diagnosed with colorectal cancer from the year that organised colorectal cancer screening programmes 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 programmes.

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. 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 colorectal cancers.

In total, 228 667 colorectal cancer cases were included in this analysis. Proportions of screen-detected cancers varied widely across countries and regions. The highest proportions of 40% to 60% were found in Slovenia and the Basque Country in Spain, where FIT-based programmes 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 programme 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% for screen detected versus 26.4–35.7% in case of non-screen detected) and less often in the proximal colon (19.5–29.9% for screen detected versus 24.9–32.8% in case of non-screen detected) with p ≤ 0.02 for each country, more often at stage I (35.7–52.7% for screen detected versus 13.2–24.9% in case of non-screen detected), and less often at stage IV (5.8–12.5% for screen detected versus 22.5–31.9% in case of non-screen detected) with p < 0.0001 for each country.

The authors concluded that the proportion of colorectal cancer cases detected by screening varied widely between countries and regions. However, in all countries, screen-detected cancers had a more favourable stage distribution than cancers detected otherwise. There is a need for improving early detection of colorectal cancer across all colorectal segments, and particularly in the proximal colon and rectum.

The study was funded by Deutsche Krebshilfe.

Reference

Cardoso R, Guo F, Heisser T, et al. Proportion and stage distribution of screen-detected and non-screen-detected colorectal cancer in 9 European countries: an international, population-based study. The Lancet Gastroenterology & Hepatology; Published online 10 May 2022.  DOI: https://doi.org/10.1016/S2468-1253(22)00084-X

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