Porphyria cutanea tarda increases risk of hepatocellular carcinoma and premature death: a nationwide cohort study

Background: Porphyria cutanea tarda (PCT) is a skin disorder originating from a deficit of the liver enzyme uroporphyrinogen decarboxylase. PCT may be a risk factor for hepatocellular carcinoma (HCC) and other cancers, but the evidence is unclear. We aimed to investigate cancer and premature mortality risk in persons with PCT.

Methods: The cohort study consisted of all Norwegian residents from 18 years between 2000 and 2016 (n = 5.4 million). 612 persons with PCT, and all cancer diagnoses and causes of death were identified through record linkage between national registries. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were adjusted for age, sex, education and calendar years. We additionally compared persons with PCT to persons with a history of chronic alcohol abuse (n = 30,468).

Results: Persons with PCT were more likely to be diagnosed with HCC [adjusted HR (aHR) = 19.7, CI = 8.8-44.0) and gallbladder and biliary tract cancer (aHR = 6.8, CI = 2.2-21.0) than the reference population. A moderate increased risk for HCC (aHR = 3.1, CI = 1.2-7.7) and gallbladder and biliary tract cancer (aHR = 4.0, CI = 1.1-14.4) remained when compared to persons with a history of chronic alcohol abuse. Additionally, compared to the reference population, persons with PCT had an increased risk of premature death (aHR = 1.5, CI = 1.2-1.7), due to the following causes of death: malignant neoplasms (aHR = 1.4, CI = 1.0-1.9), diseases of the liver (HR = 5.5, CI = 2.5-12.2), and drug and alcohol overdose (HR = 9.9, CI = 4.7-20.8).

Conclusions: Persons with PCT had an increased risk of HCC and cancer of the gallbladder and biliary tract, as well as premature death. Although most of our findings can likely be explained by common lifestyle risk factors, something inherent in PCT may contribute to the development of HCC.