Kim, Ji Ah

Abstract Background : Studies have proposed an inverse association between allergic diseases and cancer risk, but few studies to date have specifically investigated the risk of primary liver cancer (hepatocellular carcinoma, HCC; intrahepatic cholangiocarcinoma, ICC) in patients with or without allergic diseases. Objective : The aim of this study was to evaluate the association between allergic diseases and risk of developing liver cancer.Methods: A retrospective cohort study of the Korean National Health Insurance Service database was performed to study 405,512 South Korean adults ages 40 and above who underwent routine health screening after January 1st, 2005. All participants were followed for liver cancer diagnosis or death until December 31st, 2013. Those who died before the index date, had pre-diagnosed cancer, or did not undergo health screening were excluded. Cox proportional hazards regression was performed to determine the adjusted hazard ratios(aHRs) and 95% confidence intervals (CIs) for risk of developing liver cancer according presence or absence of atopic dermatitis, asthma and allergic rhinitis.Results: The aHR (95% CI) for overall liver cancer among allergic patients was 0.72 (0.64-0.81). Allergic patients had significantly reduced risk of HCC (aHR: 0.70, 95% CI: 0.61-0.81) but not ICC (aHR: 0.99, 95% CI: 0.71-1.08). Presence of allergic diseases was associated with significantly lower risk of liver cancer in both patients with (aHR: 0.61, 95% CI: 0.47-0.8) or without (aHR: 0.74, 95% CI: 0.65-0.85) chronic Hepatitis B/C infections. Presence of allergic diseases was associated with significantly lower risk of liver cancer in patients without cirrhosis (aHR: 0.72, 95% CI 0.63-0.82), but not in those with cirrhosis (aHR: 0.98, 95% CI 0.68-1.41). Patients with multiple allergies had even lower risk of liver cancer compared to patients with single allergy. Conclusion: Patients with allergic diseases have significantly lower risk of developing liver cancer compared to those without allergic diseases, which supports the rationale for immunotherapy as an effective treatment of liver cancer.