Childbirths and Breast Cancer Risk
Study Shows Full-Term Pregnancy Provides Some Protection
April 20, 2006 -- Full-term pregnancypregnancy provides a similar level of protection against breast cancerbreast cancer to women who are genetically predisposed to develop the disease and those who are not, findings from a European study show.
For women who have a child, each additional full-term child that a woman with BRCA 1 and BRCA 2 genetic mutations carried reduced her breast cancercancer risk by 14%, researchers reported. This was limited to women over 40 years of age.
While significant, this risk reduction is small compared with other interventions available to women with BRCA mutations, researcher Douglas F. Easton, PhD, of Cambridge University says.
"These findings can best be used to help us better understand risk among women with BRCA mutations," Easton tells WebMD. "I do not think there are public health implications in terms of instructing at-risk women about reproductive issues."
Up to 80% Lifetime Risk
A woman who carries a BRCA mutation has a 65% to 80% chance of developing breast cancer during her lifetime.
While it is well recognized that childbirth protects against breast cancer in women without a genetic susceptibility to the disease, its impact on BRCA mutation carriers has been less clear.
There has even been some suggestion that pregnancy increases breast cancer risk in women who are genetically predisposed to developing the disease.
In the normal-risk population, the number of children a woman has and the age at which she has them influence breast cancer risk. According to the National Cancer Institute, a woman who has her first child after the age of 35 has roughly twice the risk of developing breast cancer during her lifetime as a woman who gives birth before the age of 20.
In the new study, researcher Nadine Andrieu, of the Institut Curie in Paris, and colleagues wanted to find out if the same association held true for women with BRCA 1 and BRCA 2 mutations.
The researchers retrospectively reviewed interviews with 1,601 women with BRCA mutations enrolled in an international study. About half of the women had been diagnosed with breast cancer.