Benign ovarian teratomas: a population-based case-control study.

We attempted to identify all cases of benign ovarian teratoma which occurred in two health districts in the UK during a 56 month period. The crude incidence was 8.9 cases/100,000 women. One hundred and twenty cases and 119 age-matched controls were interviewed to identify risk factors for this disease. In addition, 137 mothers completed postal questionnaires. Cases were older at leaving school, had higher social class occupations, were more often unmarried or married late, and had fewer children than controls. Oral contraceptive use was similar for both. Cases reported more exercise at all ages, and more alcohol consumption 1 year before diagnosis. Cases' mothers reported slightly less nausea during pregnancy than controls' mothers, and none of the mothers reported exogenous hormone exposure during the index pregnancy. In this study benign ovarian teratomas strongly resemble testicular cancer in their age distribution in the population. They also resemble testicular cancer in their association with educational status and marital status. There was, however, no similarity regarding prenatal hormone exposure. The increased risks associated with exercise and alcohol use were unexpected; we need further information about how these exposures affect the ovary, and whether they affect the testis.