Safety of cyproterone acetate: report of active surveillance

Concern about a potentially increased risk of liver cancer associated to cyproterone acetate (CPA) treatment led to a postmarketing long-term surveillance study with historic accural of four groups of patients with sexual-hormonal disorders under treatment with CPA. The aim of the study was to provide a description of potential ADRs under CPA treatment with special emphasis on liver cancer. A long-term follow-up of 2506 patients was conducted. Six hundred and two persons were followed up retrospectively for longer than 10 years. In 16,721 patient-years of observation after the first CPA dose no malignant liver tumour was observed, whereas six would have been expected in this cohort. Seven incident, non-fatal benign liver tumours were found. Altogether 9.6% of a subset of 1685 patients with reported liver tests had, at some time, elevated liver enzymes. No cases were reported where CPA therapy had been discontinued due to severe liver disorder. We concluded from this active surveillance project, that CPA treatment is probably safe in the groups of patients followed up. Even though there was not a single case of liver cancer detected, the hypothesis of an elevated risk is being tested in an ongoing collaborative European case-control study which is examining the association of CPA use and primary hepatocellular cancer.