The influence of reproductive and hormonal factors on ovarian cancer survival.

Reproductive and hormonal exposures are known to influence ovarian carcinogenesis, but little is known about the effect of these factors on survival. We have studied survival according to hormonal and reproductive history in a population-based cohort of 676 Australian women aged 18-79, newly diagnosed with invasive epithelial ovarian cancer in the early 1990s. In order to place our findings in context, we have also undertaken a systematic review of the pertinent literature. Detailed information about each woman's reproductive and contraceptive history was obtained from pregnancy and contraceptive calendars at the time of diagnosis. Cox regression was used to obtain multivariate adjusted hazard ratios (HR) and 95% confidence intervals (CI). A total of 419 (62%) of the 676 women died during the follow-up (giving a 5-year survival proportion of 44%). Apart from better survival for women who had ever breastfed (multivariate HR 0.74, 95% CI 0.55-0.98), we found no association between survival from invasive ovarian cancer and a range of hormonal and gynecological factors including parity, use of oral contraceptives, and histories of tubal sterilization or hysterectomy. Systematic review of the literature generally supported the lack of influence of these factors on survival from ovarian cancer. We conclude that, except for a possible survival advantage among women with a history of breastfeeding, reproductive and hormonal exposures prior to diagnosis do not influence survival from invasive ovarian cancer, in contrast to their substantial effects on etiology of this disease.