Antibiotic exposure is associated with an increased risk of cancer: a systematic review and meta-analysis

Background: Several epidemiological studies have assessed the association between the use of antibiotics and cancer risk, but the results were inconsistent. Objective The objective of this study was to perform a meta-analysis to further evaluate possible association between antibiotic exposure and the risk of cancer. Methods We searched PubMed,Embase,Web of Science,and Chinese databases for studies on the association between antibiotic use and cancer without time restrictions. The risk estimates (hazard ratio (HR) or relative risk (RR) or Odds ratio (OR)) with their corresponding 95% confidence interval (CI) were calculated. Results A total of 23 observational studies with 19 case-control and 4 cohort studies were included in the meta-analysis. Exposure to antibiotics significantly increased the risk of cancer with an OR of 1.20 (95%CI 1.13-1.27, P=0.000). Subgroup meta-analysis by gender showed that the effect of antibiotic use on cancer risk was greater in male (34%) compared with that in female (19%). On the other hand, the risk of cancer increased with an increasing number of antibiotic prescriptions and the increasing cumulative days of antibiotic exposure. Moreover, of the 7 antibiotic types included, the six classes of antibiotics (penicillin, macrolides, quinolones, sulfonamides, tetracycline, cephalosporins) were associated with the increased risk of cancer. Further, of the 16 separate cancers included, exposure to antibiotics increased the risk of eight common cancer types (liver cancer, colorectal cancer, stomach and small intestine cancer, lymphomas, breast cancer, lung cancer, prostate cancer, and renal and bladder). Conclusions Exposure to common antibiotic types may increase the risk of the eight common cancer types in the studies population, especially in male, and the cancer risk increases with increasing antibiotic exposure intensity.