Reproductive risk factors for epithelial ovarian cancer according to histologic type and invasiveness

PURPOSE: Differences in histology among the subtypes of epithelial ovarian tumors suggest possible differences in their etiologies. We examined reprod uctive risk factors for epithelial ovarian cancer according to histologic s ubtype and tumor invasiveness. METHODS: We conducted a population-based, case-control study of association s between reproductive risk factors and epithelial ovarian cancer in the De laware Valley from 1994 to 1998. Cases age 20 to 69 years with a recent dia gnosis of epithelial ovarian cancer (n = 767) were compared to community co ntrols (n = 1367) frequency matched by age. RESULTS: With few exceptions, we found significant risk reduction for each histologic subtype of epithelial ovarian cancer by using oral contraceptive , bearing children, and having a tubal ligation; for each subtype, there wa s significant increased risk associated with a family history of the diseas e. There were no significant differences among histologic subtypes in the m agnitude of the odds ratios for OC use, parity, breastfeeding, tubal ligati on, hysterectomy, family history of breast or ovarian cancer, use of noncon traceptive estrogens, age at menarche, and age at menopause. There were als o few differences between invasive and borderline tumors, except that women with borderline tumors were significantly younger than women with invasive disease (44.7 years vs. 52.0 years, p < 0.001). Among serous tumors only, women with borderline tumors were more likely to use oral contraceptives th an women with invasive tumors (OR 2.28 95% CI 1.20-4,35). CONCLUSION: The results of this study suggest that reproductive risk factor s do not differ among histologic subtypes of epithelial ovarian cancers. (C ) 2001 Elsevier Science Inc. All rights reserved.