Risk Factors Associated With Early-Onset Colorectal Cancer

Background & aims: The incidence of colorectal cancer (CRC) is increasing in individuals younger than 50 years, who do not usually undergo screening if they are of average risk. We sought to identify risk factors for CRC in this population.

Methods: We compared sociodemographic and medical characteristics of patients who received a diagnosis of CRC at an age of 18-49 years (early-onset) with patients who received a diagnosis of CRC at an age of 50 years or older (late-onset) and with age-matched, cancer-free individuals (controls) at a tertiary academic hospital. We collected data from all adult patients with a diagnosis of CRC from January 1, 2011 through April 3, 2017 from electronic health records. Associations with risk factors were assessed using univariable and multivariable logistic regression models.

Results: We identified 269 patients with early-onset CRC, 2802 with late-onset CRC, and 1122 controls. Compared with controls, patients with early-onset CRC were more likely to be male (odds ratio [OR], 1.87; 95% CI, 1.39-2.51), have inflammatory bowel disease (IBD) (3% vs 0.4% for controls; univariable P < .01), and have a family history of CRC (OR, 8.61; CI, 4.83-15.75). Prevalence values of well-established modifiable CRC risk factors, including obesity, smoking, and diabetes, were similar. Compared to patients with late-onset CRC, patients with early-onset CRC were more likely to be male (OR, 1.44; 95% CI, 1.11-1.87), black (OR, 1.73; 95% CI, 1.08-2.65) or Asian (OR, 2.60; 95% CI, 1.57-4.15), and have IBD (OR, 2.97; 95% CI, 1.16-6.63) or a family history of CRC (OR, 2.87; 95% CI, 1.89-4.25). Sensitivity analyses excluding IBD and family history of CRC showed comparable results. Early-onset CRC was more likely than late-onset disease to be detected in the left colon or rectum (75% vs 59%, P = .02) and at a late stage of tumor development (77% vs 62%, P = .01).

Conclusions: In a retrospective study of patients with early-onset CRC vs late-onset CRC or no cancer, we identified non-modifiable risk factors, including sex, race, IBD, and family history of CRC, to be associated with early-onset CRC.