Objective: A case-control study was conducted to investigate the effects of reproductive and dietary risk factors on ovarian cancer risk in China.
Methods: Cases were 254 patients with histologically confirmed epithelial ovarian cancer. Controls were 652 women without neoplasm and long-term dietary modifications. Information was collected using a structured questionnaire on sociodemographic and reproductive characteristics, diet, medical and family cancer history. The risks of ovarian cancer were assessed by multivariate logistic regression analysis.
Results: The adjusted odds ratios (OR) for women having at least two full-term pregnancies, two or more incomplete pregnancies, and first full-term pregnancy at 21-25 years of age were 0.45 (95% CI 0.3-0.8), 0.56 (95% CI 0.4-0.8), and 0.40 (95% CI 0.2-0.8), respectively, compared with nulliparity. The OR of ever lactation was 0.50 (95% CI 0.3-0.8) and oral contraceptive was 0.48 (95% CI 0.3-0.7), while postmenopausal women appeared to have an increased risk with OR 1.48 (95% CI 1.0-2.3). For the highest versus the lowest quartile intakes of nutrients, the OR were 2.17 (95% CI 1.3-3.8) for fat, 0.36 (95% CI 0.2-0.6) for fibre, 0.26 (95% CI 0.2-0.5) for carotene, 1.59 (95% CI 0.9-2.7) for retinol, 0.31 (95% CI 0.2-0.5) for vitamin C, and 0.41 (95% CI 0.2-0.7) for vitamin E, with significant dose-response relationships.
Conclusion: It is evident that full-term and incomplete pregnancies, lactation, and oral contraceptive use can reduce the ovarian cancer risk. Moreover, consumption of foods low in fat but high in fibre, carotene and vitamins appears to be protective against ovarian cancer in Chinese women.