| Abstract |
Background: There is evidence in the recent literature that the incidence patterns of colorectal cancer (CRC) has changed considerably over the years. It has been stressed CRC incidence rates tend to rise rapidly in individuals under 50 years old compared with older adults (i.e. over 50 years). However, such data from many European countries are still lacking and this study aimed to cover this gap in the literature and the Greek data.
Aim: The current study aimed to assess the incidence of CRC in Crete during the last three decades (1992-2021), compare them among younger and older. Additionally, we explored the main established determinants for CRC incidence in young versus older adults and tested whether they differed temporally. Lastly, a secondary objective was to explore variations between younger and older adults as regards stage at diagnosis, the type of treatment-intervention and the course of the disease (i.e. multiple metastases, survival).
Methods: Data on malignant neoplasms of colon (ICD-10: C18), rectosigmoid junction and rectum (ICD-10: C19-20) have been extracted from the database of the Regional Cancer Registry of Crete for three decades (period 1992-2021). The number of these cases for the period 1992-2021 was 3,857 (n = 2895 colon and n = 962 rectum). CRC Age-Standardized Incidence Rates (ASIR/100,000/year) and Age-Specific Incidence Rates (ASpIR/100,000/year) have been analyzed. The ASIR annual percentage change (APC) was estimated per year, while projection of the expected changes was attempted using a Bayesian model. Mann-Whitney and Kruskal Wallis test, as well as binary logistic regression were performed. Net-Survival (%) was considered through Survival analysis and Kaplan-Meier Curves. The analysis was performed in the Stata, while all tests were performed at a level of statistical significance α= 0.05 and were two-tailed.
Results: The colon ASIR increased significantly from 1992 to 2021 with a statistically significant annual percentage change of 1,5 (95% CI, 1,3-1,7). Similarly, rectal ASIR presented a lower annual percentage increase (APC, 0,9%; CI 95%, 0,0-1,6). Males presented a higher incidence compared to females (55,5% and 44,5%, respectively); however, females had significantly higher increasing trends (APC, 1,8% ; 95%CI, 1,4-2,2). The mean ASpIR of colon cancer patients <50 years were 7.2/100,000/year (95% CI 5.1-9.7), while for patients > 50 years the ASpIR was 149/100,000/year (95% CI 146.2-153.4). The ASpIR seem to start declining slightly after the age of 85-89 years old. Statistically significant APC (%) were observed in most age groups (p<0,05). In particular, ASpIR presented a 29.6% increase from 2001 to 2011 in the age group of 20-34years and further increase is expected from 2022-2030 (projected change, 42.8%). Similar trends were observed in the age group of 35-49 years from 2001 to 2011. Rectal trends were in compliance with the colon trends. Focusing on the risk factors for younger adults, several variations were observed among the three time periods. BMI presented a significantly increasing RR over the years, (1992-2000, 2001-2011 and 2012-2021: RR; 1.2, 1,8, 2,5 respectively, p =0,04). BSA presented similar trends with a Pvalue for interaction<0.001. Pack years (p= 0,01), alcohol consumption (0,02) and farmers occupation (0.04) presented significantly increasing trends since 2012-2021. Lastly, it was found that 5 year Net-survival changed significantly between the two age groups among the three decades (p=0.03). Particularly, younger adults tend to present lower survival as the years goes by while older adults have rising survival trends. Additionally, younger adults presented higher percentages of diagnosis at a late stage (III & IV) from 2001 to 2021, contrary to the older adults (p=0.03). Similarly, chemotherapy tends to be more frequent in younger adults during the last two decades comparing to 1992-2000 (p=0.04).
Conclusions: We confirmed an increased incidence of CRC in young adults <50s in a European population with low cancer incidence in the past and a worrisome prediction for the near future. Several risk factors were found to deteriorate in this age group, as the years goes by. Further studies are required to fully understand the underlying factors that cause these trends, which clearly indicate the need to empower efforts towards clinical research, rising awareness among patients and physicians about the unique characteristics of early-onset CRC. Lastly, starting CRC screening at an earlier age may be essential.
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Colorectal cancer incidence in Crete during the last 30 years. : Longitudinal differences between younger and older adults and determinants
