Systematic review with meta-analysis: bariatric surgery reduces the incidence of hepatocellular carcinoma

Background Obesity is a risk factor for non-alcoholic steatohepatitis (NASH) and increases the risk of several cancer types including cancers of the liver. Bariatric surgery can provide durable weight loss, but little is known about the later development of hepatocellular carcinoma (HCC) after surgery. Aim To determine whether bariatric surgery reduces the risk of HCC. Methods We performed a comprehensive literature search of major databases (from inception to November 2020) to identify studies which assess the incidence and risk of HCC following bariatric surgery. Pooled data were assessed using a random-effects model expressed in terms of odds ratio (OR), incidence rate ratio and 95% confidence interval (CI). Results Nine studies (two abstracts and seven full texts) were included for meta-analysis which involved 19 514 750 patients (18 423 546 controls and 1 091 204 bariatric patients). Pooled unadjusted odds ratio (OR) was 0.40 (95% CI: 0.28-0.57) which favoured bariatric surgery, though with high heterogeneity (I-2: 79%). Using an adjusted model derived from matched cohorts (five studies) yielded an OR of 0.63 (95% CI: 0.53-0.75) with moderate heterogeneity (I-2: 38%). The pooled rate/1000 person-years was 0.05 (95% CI: 0.02-0.07) in bariatric surgery patients and 0.34 (95% CI: 0.20-0.49) in the control group with an incidence rate ratio of 0.28 (95% CI: 0.18-0.42). Conclusion Bariatric surgery is associated with a decreased risk of HCC.