Background: In the regions of the world with the highest occurrence of colorectal cancer (North America, Europe, and Australia and New Zealand), the overall incidence remained stable and mortality declined in recent decades. In contrast, colorectal cancer incidence and mortality in individuals younger than 50 years (early-onset) has increased during the past three decades.
Aim: Several studies have identified lifestyle factors associated with risk of colorectal cancer overall; however, apart from genetic predisposition, there is almost nothing known of the risk factors for early-onset colorectal cancer.
Methods: A case-control study was performed using 3007 incident colorectal cancer cases diagnosed age before 50 years who were recruited into the Colon Cancer Family Registry through population cancer registries in Australia, Canada and the USA, compared with 3611 controls randomly selected from the general population (population-controls) and 2964 of the cases’ siblings without diagnosis of any cancer (sibling-controls). Using multivariable logistic regressions, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for associations of early-onset colorectal cancer with potential environmental risk factors.
Results: An increased risk of early-onset colorectal cancer was associated with increased body mass index (BMI) at age 20 years (OR per 5-kg/m2 1.23, 95%CI 1.10-1.36), increased recent BMI (OR per 5-kg/m2 1.16, 95%CI 1.08-1.24), increased BMI from age 20 years to recent age (OR per 5-kg/m2 1.09, 95%CI 1.00-1.19), diabetes (OR 1.52, 95%CI 1.00-2.31), and red meat consumption (OR per serving 1.20, 95%CI 1.06-1.36) while a decreased risk was associated with aspirin and NSAIDs intake (OR ever vs never 0.39 , 95%CI 0.33-0.47) when compared with population-controls after adjusting for potential confounders. Similar associations were observed when compared with sibling-controls.
Conclusions: Similar to colorectal cancers overall, we observed that increased body mass, diabetes and read meat consumption increase risk of early-onset colorectal cancer while aspirin intake reduces their risk.