Parity and Oral Contraceptive Use in Relation to Ovarian Cancer Risk in Older Women
A partir de données issues de 3 cohortes américaines incluant un total de 310 290 femmes blanches âgées de plus de 50 ans, cette étude évalue l'association entre la parité, l'utilisation d'une contraception orale et le risque de cancer de l'ovaire après la ménopause
Background: Several studies have suggested that the ovarian cancer risk reductions associated with parity and oral contraceptive use are weaker in postmenopausal than premenopausal women; yet little is known about the persistence of these reductions as women age. This question gains importance with the increasing numbers of older women in the population. Methods: We addressed the question using data from three large US cohort studies involving 310,290 white women aged 50+ years at recruitment, of whom 1815 developed subsequent incident invasive epithelial ovarian cancer. We used Cox regression, stratified by cohort, to examine age-related trends in the hazard ratios per full-term pregnancy and per year of oral contraceptive use. Results: The parity-associated risk reductions waned with age (P < 0.001 for trend in hazard ratio with increasing age), particularly among women aged 75 years or more, for whom we observed no association with parity. However we observed no such attenuation in the oral-contraceptive-associated risk reductions (P = 0.79 for trend in hazard ratio with increasing age). Conclusion: These findings suggest that prior oral contraceptive use is important for ovarian cancer risk assessment among women of all ages, while the benefits of parity wane as women age. Impact: This information, if duplicated in other studies, will be useful to preventive counseling and risk prediction, particularly for women at increased ovarian cancer risk due to a personal history of breast cancer or a family history of ovarian cancer.