Prior oral contraceptive use is associated with reduced risk for ovarian cancer among women of all ages; however, risk reductions associated with childbirth diminish as women age, a study published online first in the journal Cancer Epidemiology, Biomakers & Prevention has shown.
Childbirth and oral contraceptive use is known to contribute to a reduced risk of ovarian cancer in premenopausal women. But little is known about the effect of age on this link; therefore, the researchers sought to determine whether associated risk reductions were sustained as women aged.
The researchers examined age-related trends in the hazard ratios per full-term pregnancy and per year of oral contraceptive use in 310 290 white women from 3 large US cohort studies of women older than 50 years at recruitment, including 1815 of whom developed incidence invasive epithelial ovarian cancer. The researchers used Cox regression, stratified by cohort, in their review of the data.
Results demonstrate that risk reductions associated with childbirth waned as women aged (P < .001 for trend in hazard ratio with increasing age), and no association with childbirth was seen in women age 75 years or older. However, risk reductions associated with oral contraceptive use did not diminish with age (P = .79 for trend in hazard ratio with increasing age).
These results can be used in risk prediction and to guide counseling for women, particularly those at higher risk due to personal history of breast cancer or a family history of ovarian cancer. However, these results should be validated in other studies.
1. McGuire V, Hartge P, Liao LM, et al. Parity and oral contraceptive use in relation to ovarian cancer risk in older women [published online ahead of print April 12, 2016]. Cancer Epidemiol Biomakers Prev. doi:10.1158/1055-9965.EPI-16-0011.