Cancer risk in patients with hereditary hemochromatosis and in their first-degree relatives

Background & Aims: Iron overload may be carcinogenic. Patients with hereditary hemochromatosis (HH) are reportedly at a 20-200-fold risk of intrahepatic cancer, but the reported risks for nonhepatobiliary cancers are conflicting. The risk of cancer in heterozygous individuals (estimated allele frequency, 1/10 to 1/20) is unknown. This study aimed to better assess these risks. Methods: We performed a population-based cohort study of 1847 Swedish patients with HH and 5973 of their first-degree relatives using nationwide, population-based health and census registers. We used standardized incidence ratios (SIRs) as relative risk. Results: With 62 liver cancers and 128 nonhepatobiliary cancers, patients with HH were at a 20-fold risk of liver cancer (SIR, 21; 95% confidence interval [Cl], 16-22) but an almost unaltered risk of all other cancers (SIR, 1.2; 95% Cl, 1.0-1.4), including nonelevated risks for several gastrointestinal tract cancers. At 10 years of follow-up, the absolute risk of liver cancer was 6% among men and 1.5% among women. With 21 liver cancers and 508 nonhepatobiliary cancers, first-degree relatives were at an unaltered risk of extrahepatic cancer (SIR, 1.0; 95% Cl, 0.9-1.1, including unelevated risks for gastrointestinal cancers) but at a modest and historic increased risk of hepatobiliary cancer (SIR, 1.5; 95% Cl, 1.0-2.4), the histopathologic spectrum of which differed from the patients. Conclusions: Patients (particularly men) with HH are at increased risk for hepatocellular cancer, although the magnitude of the risk is lower than previous estimates. Overall cancer risk in first-degree relatives does not seem to be increased.