Treatment patterns and survival outcomes of early-onset colorectal cancer patients in Alberta, Canada: a population-based study

Background: The incidence of early-onset (<50) colorectal cancer (eoCRC) has been increasing in Canada. Little is known about treatment patterns and outcomes among this patient population in Canada. Patients and methods: We conducted a retrospective population-based cohort study of CRC patients in Alberta (2010-2018) using electronic medical records and administrative claims data. Treatment patterns and CRCspecific mortality were compared between early-onset age groups (<40 and 40-49) and average age-at-onset (60-70) (aoCRC) patients with multivariable logistic regression and cox proportional hazard models. Results: There were 334 and 935 patients in the early-onset groups and 4606 in the aoCRC group. Compared with aoCRC, patients <40 were more likely to receive chemotherapy in stage II colon (OR 3.41, CI 1.75-6.47) and stage III rectal (OR 3.01, CI 1.18-10.21), and to receive systemic therapy (OR 2.40, CI 1.46-4.12) and radiation in stage IV CRC (OR 2.70, CI 1.48-4.92). The 40-49 age group was more likely to receive chemotherapy in stage II colon (OR 2.13, CI 1.25-3.56), and chemoradiation in stage II rectal (OR 2.16, CI 1.25-3.80) and stage III rectal (OR 1.63, CI 1.13-2.40), as well as systemic therapy in stage IV CRC (OR 2.46, CI 1.75-3.52). Survival did not differ between <40 and 60-70 age groups. Survival was significantly higher for the 40-49 age group, but only in stage IV (HR 0.79, CI 0.67-0.94). Conclusions: EoCRC patients tended to receive more therapy than average age CRC patients with minimal survival gains. Additional research to identify optimal treatment strategies for eoCRC patients is required.