The roles of exogenous sex hormones and reproductive factors in the causation of malignant melanoma of the skin in women were examined in a case-control study of 276 patients and 276 matched controls in Western Australia. There was no consistent evidence of a relationship between the incidence rates of different histogenetic types of melanoma and age at menarche, duration of menstrual life, degree of obesity, number of pregnancies more than 20 weeks in duration or use of oral contraceptive preparations (OCP). Exposure to OCP was examined separately for different age periods and in different intervals of time before diagnosis; no consistent trend emerged. There was borderline evidence of an association of superficial spreading melanoma with duration of use of unopposed oestrogens. On the basis of seven studies of the relationship of melanoma to OCP published to date, we estimate that the total incidence rate of melanoma in OCP ever-users is unlikely to be increased by more than one third the rate in never-users.
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