Colorectal Cancer Risk in Patients with Breast Cancer Survivors: Evidence from a Comprehensive Cancer Center

Abstract

Purpose: Previous epidemiological and observational studies have yielded conflicting results about incidence of colorectal cancer in patients with breast cancer. With increasing effectiveness of treatment regimens and increasing patient survivability, there is a paucity of data about the necessary frequency of high risk screening measures in this patient subpopulation. Methods: We conducted a retrospective cohort study among long term survivors (breast cancer free patients) on regular surveillance. The medical records of the patients was systematically reviewed by two independent physicians to collect relevant information including results of their index colonoscopy. Incidence rate ratios (RR) and 95% confidence intervals (95% CI) were calculated. Results: Our study included 303 patients with a follow up over 2232 person years. One patient was diagnosed with colonic adenocarcinoma. The RR of villous adenoma in patients over 50 years of age was 1.80 (95% CI 0.10- 32.06). RR of Tubular adenoma in patients more than and less than 50 years of age was 1.48 (95% CI 0.55-3.96) and 0.67 (95% CI 0.25-1.78) respectively. In patients with a family history of colorectal cancer the RR of development of villous adenoma was 3.37 (95% CI 0.57-19.67) and of tubular adenoma was 0.70 (95% CI 0.29- 1.70). Among patients on an estrogen antagonist, the RR of development of villous adenoma was 1.91 (95% CI 0.21-16.88) while that of tubular adenoma was 0.92 (95% CI 0.50-1.67). Conclusion: The results of our study indicate that age, family history of colon cancer and use of estrogen inhibitors are not a risk factor for development of advanced adenomas in this patient population. It is inferred that long term survivors of breast cancer are not an increased risk of premalignant and malignant lesions of colon in comparison with general population.FigureTable: Incidence of neoplastic lesions in breast cancer survivors