Infection,antibiotic therapy and risk of colorectal cancer: A nationwide nested case–control study in patients with Type 2 diabetes mellitus

Patients with Type 2 diabetes mellitus are at a higher risk of colorectal cancer (CRC). The objective of our study was to examine the inter‐relationship among infection sites, systemic antibiotic use and risk of CRC among patients with Type 2 diabetes mellitus. From a diabetic cohort from the Taiwan's National Health Insurance claims database, we identified 3,593 incident colon cancer cases, 1,979 rectal cancer cases and 22,288 controls and conducted a nested case–control study to examine the association between antibiotic use and CRC incidence. Logistic regression models were applied to estimate the odds ratio (OR) and the 95% confidence interval (95% CI) between infection sites, antibiotic use and CRC incidence. Patients with intra‐abdominal infection were significantly associated with increased risk for colon cancer (OR = 2.01, 95% CI = 1.73–2.35) and rectal cancer (OR = 1.59, 95% CI = 1.26–2.00). Any antianaerobic antibiotic use was associated with a higher risk of colon cancer (OR = 2.31, 95% CI = 2.12–2.52) and rectal cancer (OR = 1.69, 95% CI = 1.50–1.90) but without an obvious dose–response relationship for cumulative use. Antianaerobic antibiotics also increased the risks for those with nonintra‐abdominal infection. No association was found between antiaerobic agent use and the CRC risk. The results suggest intra‐abdominal infections and antianaerobic antibiotic use may be a marker for precancerous lesions or early CRC, although the possibility of antianaerobic antibiotics playing an additional role cannot be excluded. Further research examining the relationship between intra‐abdominal infection, antianaerobic antibiotics use and possible change of microbiota leading to colorectal carcinogenesis is warranted.