Proportion and rate of distribution of colorectal cancer detected on screen and undetected on screen in nine European countries: an international population study
Background
The effects of recent colorectal cancer screening programs in Europe on colon and rectal cancer mortality will take several years to become fully known. We wanted to analyze the characteristics and parameters of screening programs, the proportions of colorectal cancer detected by screening, and the distribution of stages in unsuccessful colorectal cancer screening, to ensure timely assessment of possible effects of screening programs in several European countries. countries.
Methods
This population study was conducted in nine European countries for which data on the method of detection were available (Belgium, Denmark, England, France, Italy, Ireland, the Netherlands, Slovenia and Spain). Data from 16 population registries of cancer were included. Patients were included if they were diagnosed with colorectal cancer from the year when organized screening programs for colorectal cancer were conducted in each country until the last year with available data at the time of analysis, and if their age at diagnosis belonged to the age groups targeted by the programs. Data collected included sex, age at diagnosis, date of diagnosis, topography, morphology, clinical and pathological information of TNM based on the release that was in place at the time of diagnosis, and mode of detection (i.e., detected on screen or detected without screen). If rate information was not available, patients were not included in rate-specific analyzes. The primary outcome was the proportion and rate of distribution of colon and rectal cancer detected on screen compared to undetected.
Findings
228,667 cases of colorectal cancer were included in the analyzes. The proportion of cancers detected on the screen varied widely between countries and regions. The largest share (40-60%) was in Slovenia and the Basque Country in Spain, where FIT-based programs were fully implemented and the participation rate was higher than 50%. A similar proportion of cancers detected on screen was also found in 2015 for the Netherlands, where participation was more than 70%, although the program has not yet been fully implemented for all age groups. In most other countries and regions, the proportion of cancers detected on the screen was below 30%. Compared to cancers not detected by screening, cancers detected by screening were much more commonly detected in the distal colon (range 34.5-51.1% of those detected by screening). vs 26.4-35.7% detected without screen) and less common in the proximal colon (19.5-29.9% detected screen) vs 24.9-32.8% of detected screen) p≤0.02 for each country, more frequently at level I (35.7-52.7% of detected screen vs 13.2–24.9% of detected screen) and less frequently in stage IV (5.8–12.5% of detected screen)
vs 22.5–31.9% detected without screen) p <0.0001 for each country.
Interpretation
The proportion of cases of colorectal cancer detected by screening varied widely between countries. However, in all countries, cancers detected on screen had a more favorable distribution by grade than cancers detected differently. There is still much need and opportunity to improve early detection of cancer in all segments of the colorectum, especially in the proximal colon and rectum.
Financing
Deutsche Krebshilfe.