Borderline ovarian tumors possess many of the same morphological features as their malignant counterparts, but they do not destructively invade the ovarian stroma, and the women in whom they develop generally have a favorable prognosis. Female residents of three urban counties of western Washington diagnosed with serous and mucinous borderline ovarian tumors between 1980 and 1985 (n = 116) were interviewed regarding past reproductive events. A random sample of women from the same counties (n = 158) was identified through random digit dialing and were interviewed. The risk of these ovarian tumors among women who had given birth to 1 or 2 children and to 3 or more children was, respectively, 0.7 and 0.4 that of nulliparous women. There was no consistent influence of increasing age at first live birth. Adjusting for parity, a history of lactation was associated with a 50% reduction in risk. Among nulliparous women, a further increase in risk was present in those who reported a history of infertility. Use of oral contraceptives was associated with a 60% reduction in risk. However, the size of the association was not dependent on duration, age at first use, or years since last usage. In conclusion, borderline tumors appear to have similar epidemiological patterns with regard to reproductive events as their more malignant counterparts.
PIP: Women residing in 3 urban counties of western Washington State diagnosed with serous and mucinous borderline ovarian tumors or grade 1 malignancies, between 1980 and 1985 were interviewed to assess risk factors related to reproductive history. 121 subjects were interviewed in person, and compared to 158 controls ascertained and interviewed by random sampling via telephone. The stratified analysis technique, adjusting for parity, revealed a 60% reduction of risk in users of oral contraceptives, although neither duration, nor age at 1st use or years since last use of pills had any effect. Similarly, lactation reduced risk 50%, without any influence of duration. The reduction in risk with pill use was largely confined to women who had their 1st child after age 21. Having had 1 or 2 children conferred 0.7 of the risk of nulliparas, and 3 or more children 0.4. A history of miscarriage, but not of induced abortion, was more common in cases than in controls. History of tubal ligation was negatively correlated with borderline tumors, in women whose sterilization was less than 12 years before diagnosis. In general, borderline tumors have similar epidemiological patterns to those of malignant ovarian tumors, with-increased risk for nulliparas, women reporting infertility, those who have used oral contraceptives, and those who have not lactated.