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WEDNESDAY, March 13, 2019 (HealthDay News) — The correlation between reproductive events and breast cancer risk varies for BRCA1<\/i> and BRCA2<\/i> mutation carriers, according to a study published March 8 in JNCI Cancer Spectrum<\/i>.<\/p>\n
Mary Beth Terry, Ph.D., from Columbia University in New York City, and colleagues examined whether reproductive events are associated with breast cancer risk in a retrospective cohort with 5,707 BRCA1<\/i> and 3,525 BRCA2<\/i> mutation carriers and a prospective cohort of 2,276 BRCA1<\/i> and 1,610 BRCA2<\/i> mutation carriers.<\/p>\n
The researchers observed no correlation with parity versus nulliparity for BRCA1<\/i> mutation carriers (combined hazard ratio [HRC<\/sub>], 0.99; 95 percent confidence interval [CI], 0.83 to 1.18). An increased number of full-term pregnancies was correlated with reduced breast cancer risk relative to being uniparous (HRC<\/sub>s, 0.79 [95 percent CI, 0.69 to 0.91]; 0.7 [95 percent CI, 0.59 to 0.82]; and 0.5 [95 percent CI, 0.4 to 0.63] for two, three, and at least four full-term pregnancies, respectively); increased breastfeeding duration was correlated with reduced breast cancer risk. Uniparous BRCA1<\/i> mutation carriers had an increased breast cancer risk relative to nulliparous women in the prospective analysis (prospective HR, 1.69; 95 percent CI, 1.09 to 2.62). Being parous was correlated with an increased risk for breast cancer for BRCA2<\/i> mutation carriers (HRC<\/sub>, 1.33; 95 percent CI, 1.05 to 1.69).<\/p>\n “These findings might help refine the [breast cancer] risk estimates and make it possible to adapt the surveillance of mutation carriers according to their reproductive life history,” the authors write.<\/p>\n