The Risk of Cancer in Patients with Benign Anal Lesions: A Nationwide Population-based Study

Abstract Objective To evaluate the risk of cancer among patients diagnosed with hemorrhoids and benign anal inflammatory lesions. Methods A population-based, retrospective cohort study was conducted that included patients diagnosed with hemorrhoids or benign inflammatory anal lesions (eg, anal fissure, fistula, and perianal abscesses) that were registered in the National Health Insurance Research Database in Taiwan between January 1, 2000 and December 31, 2010. Standardized incidence ratios (SIRs) were calculated to compare the cancer incidence of these patients to the general population. Results During a median observation period of 6.23 years, 3080 cancers developed among 70,513 hemorrhoid patients, with a follow-up period of 438,425.6 person-years, entailing the SIR of 1.52 (95% confidence interval [CI], 1.47-1.58). Increased cancer risk (SIR 1.16; 95% CI, 1.11-1.21) was still noted even after excluding the first year of observation. Significant long-term risk for colorectal cancer (SIR 1.50; 95% CI, 1.35-1.66) and prostate cancer (SIR 1.40; 95% CI, 1.17-1.66) was observed after corrections were made for multiple comparisons. In contrast, there was no remarkable increase in cancer risk for patients with inflammatory anal lesions when cancers detected within the first year of diagnosis were excluded. Conclusion The presence of hemorrhoids is associated significantly with a long-term risk of developing colorectal cancer or prostate cancer. In contrast, benign inflammatory anal lesions do not appear to increase the risk of malignancy.