"Incessant ovulation" and ovarian cancer.

A case-control study of 150 ovarian cancer patients under the age of 50 and individually matched controls was done to study the influence of fertility and oral contraceptive use on the risk of ovarian cancer. The risk decreased with increasing numbers of live births, with increasing numbers of incomplete pregnancies, and with the use of oral contraceptives. These three factors can be amalgamated into a single index of protection--"protected time"--by considering them all as periods of anovulation. The complement of protected time--viz., "ovulatory age", the period between menarche and diagnosis of ovarian cancer (or cessation of menses) minus "protected time"--was strongly related to risk of ovarian cancer. Other factors found to be associated with increased ovarian cancer risk were obesity, cervical polyps, and gallbladder disease. Women who had an "immediate" intolerance to oral contraceptive use had a fourfold increased risk of ovarian cancer. 7 patients, but no controls, could recall a family history of ovarian cancer.