Patterns of colorectal cancer diagnosis among younger adults in a real-world, population-based cohort

Lay abstract In this study, we found that the percentage of younger individuals with colorectal cancer has increased in Alberta, particularly for cancers arising from the rectum and left side of the colon. Reassessment of the recommended age to start colorectal cancer screening in Canada is needed. Aims: To review the patterns of early-onset (<50 years old) colorectal cancer (CRC) in Alberta across the past 15 years among different socioeconomic and demographic patient subgroups. Methods: This is a retrospective, population-based study based on Alberta administrative databases. Income level was identified via income information from the 2006 Canadian census. Patients with colorectal adenocarcinoma diagnosed 2004-2018 were included. Frequency analyses were used to examine the percentage of early-onset CRC cases among different subgroups over the period studied. Multivariable logistic regression analysis was used to examine factors associated with the development of early-onset CRC. Results: A total of 24,912 patients were included, of whom 2096 (8.4%) were diagnosed at age <50 years and 22,816 (91.6%) at age >= 50 years. The percentage of patients diagnosed at age <50 years increased over time (10.2% in 2018 vs 7.9% in 2004; p < 0.003). Higher income was associated with younger age at diagnosis of CRC (odds ratio [OR] for quartile 1 vs quartile 4: 0.54; 95% CI: 0.47-0.62). Other factors associated with younger age at diagnosis included female sex (OR for male vs female: 0.85; 95% CI: 0.78-0.94), distal CRC (OR: 1.66; 95% CI: 1.50-1.84) and North zone (OR for South zone vs North zone: 0.74; 95% CI: 0.60-0.92). Conclusion: The proportion of patients (out of the overall CRC population) with early-onset CRC, increased in Alberta throughout the study duration (particularly left-sided CRC). There is a need to reassess the current age limits for CRC screening in Canada in view of these findings.