Significant Rise of Colorectal Cancer Incidence in Younger Adults and Strong Determinants: 30 Years Longitudinal Differences between under and over 50s.

(1) Background: There is evidence in the recent literature that the incidence patterns of colorectal cancer (CRC) have changed considerably over the years, tending to rise rapidly in individuals under 50 years old compared with those over 50 years. The current study aimed to assess the incidence of CRC in Crete from 1992−2021 and compare them among younger and older adults. (2) Methods: Data on malignant neoplasms of colon, rectosigmoid junction, and rectum have been extracted from the database of the Regional Cancer Registry of Crete. (3) Results: The number of these cases for the period 1992−2021 was 3857 (n = 2895 colon and n = 962 rectum). The mean age-specific incidence rate (ASpIR/100,000/year) of colon cancer patients <50 years was 7.2 (95% CI 5.1−9.7), while for patients ≥50 years the ASpIR was 149 (95% CI 146.2−153.4). ASpIR presented a 29.6% increase from 2001 to 2011 in the age group of 20−34 years and further increase is expected from 2022−2030 (projected change, 42.8%). The main risk factors were the pack years (p = 0.01), alcohol consumption (0.02), and farmer occupation (0.04), especially during 2012−2021. (4) Conclusions: We confirmed an increased incidence of CRC in young adults <50 in a European population with low cancer incidence in the past and a worrisome prediction for the near future. The observed trends clearly indicate that starting CRC screening at an earlier age may be essential.