Patients with breast cancer may be at higher risk of colorectal neoplasia

Background The risk of colorectal neoplasia in breast cancer survivors is unclear. This study aimed to determine the colonic adenoma detection rate (ADR) in patients with breast cancer. Methods We conducted a retrospective study of patients with breast cancer who underwent a colonoscopy between 2000 and 2017. A control group (n=3295), comprising cancer-free patients undergoing their first screening colonoscopy, was used for comparison. Results Of 62,820 breast cancer patients, 3304 met the inclusion criteria. The mean age at the time of first colonoscopy was 59 years. ADR was 55%; 1803 patients had adenomas. High-grade dysplasia was evident in 28% of polyps and invasive adenocarcinoma was detected in 172 patients (5%). The median time from breast cancer diagnosis to adenoma detection was 3 years. The ADR was 21% in patients aged <40 years (n=63) and 39% in patients aged 40-50 years (n=314). The ADR was 26% in patients <50 years with a body mass index (BMI) lower than 30 kg/m² or no family history of colorectal cancer. Multivariate logistic regression analysis revealed that the following independent factors were associated with a greater risk of colon adenoma: older age, higher BMI, family history of colorectal cancer, and personal history of breast cancer. Conclusions In patients with breast cancer, the ADR was higher than the reported rates for the general population. Screening colonoscopy should be considered soon after breast cancer diagnosis in patients <50 years of age. Further prospective studies investigating our findings are warranted.