ORAL-CONTRACEPTIVES AND LIVER-CANCER - RESULTS OF THE MULTICENTER INTERNATIONAL LIVER-TUMOR STUDY (MILTS)

Many, but not all, previous epidemiological studies indicated a greate r risk of hepatocellular cancer (HCC) in women who have used combined oral contraceptives for a long period of time, but no one has analyzed this risk based upon use of different formulations. It was decided to analyze specifically the risk of OC containing cyproterone acetate (C PA) after toxicological experiments in animals found hints for a poten tial genotoxicity. This report describes the risk associated with ever having used combined oral contraceptives (OC) among 317 cases of prim ary hepatocellular cancer (HCC) in women under age 65, compared with 1 060 age-matched hospital and 719 population controls in a case-control study, which was conducted in six European countries. The adjusted od ds ratio (unconditional logistic regression) for ever having used any OC was found to be 0.75 (0.54 to 1.03) when all cases were compared wi th all controls, and compared to hospital and population controls sepa rately: 1.13 (0.86 to 1.48) and 0.78 (0.59 to 2.03), respectively. The adjusted odds ratios for OC containing all progestins of the CPA grou p were 0.89 (0.59 to 1.61); and 0.89 (0.37 to 2.18) for OC containing only CPA. There was no increase in risk for HCC with increasing durati on of OC use among the different groups of OCs in the total group of c ases with pooled controls. The risk estimates were not related to time since first or last use of any of the types of OCs considered. The mo st important risk factors for HCC were confirmed as a prior history of hepatitis B and C (adjusted odds ratio 3.1 (2.2; 4.3) and 37.9 (20.2; 70.9) for HBV and HCV, respectively). In the small subgroup of HCC ca ses without liver cirrhosis and with negative serology for HBV and HCV , there was evidence of an association with duration of OC use. No suc h trend was observed for the CPA group of OCs. Altogether, there is no evidence for an increased risk of HCC associated with CPA or CPA-like OCs. Oral contraceptives in the aggregate may enhance the risk of liv er carcinomas not associated with HBV or HCV infection, but if so, thi s is an extremely rare adverse effect of their use. (C) 1997 Elsevier Science Inc. All rights reserved.