Objective: To analyze the association between oral contraceptive use and the risk of benign liver tumors.
Methods: Two parallel case-control studies on hepatocellular adenoma and focal nodular hyperplasia. Collaborative study of 15 German liver centers. Cases defined by histology and compared with population controls.
Results: Fifty-one hepatocellular adenoma and 143 focal nodular hyperplasia cases (women) were recruited between 1990 and 1997, and compared to 240 population controls with a recent abdominal imaging test. The frequency age-matched odds ratio was 1.25 (95% confidence interval (CI), 0.37-4.22) and 1.96 (95% CI, 0.85-4.57) for hepatocellular adenoma and focal nodular hyperplasia, respectively. For hepatocellular adenoma, there was neither a significantly increased risk with longer duration of oral contraceptive use, nor an association with time since first or last use. For focal nodular hyperplasia, however, a slightly increased odds ratio was found with longer duration of use and more recent last use.
Conclusion: There is little evidence for an increased risk for hepatocellular adenoma in women using modern oral contraceptives. If there is a risk not detected by the limited study size, hepatocellular adenoma is an extremely rare, and focal nodular hyperplasia a rare, adverse effect potentially associated with long-term oral contraceptive use and likely to be without public health importance.