Women's risk of breast cancer can persist more than 20 years after childbirth, according to a study published online December 10 in the Annals of Internal Medicine.
Childbirth has long been understood as being protective against breast cancer, but breast cancer risk has been shown to increase shortly after childbirth, wrote researchers from the University of North Carolina. A team led by Hazel Nichols, PhD, investigated how long after childbirth the risk of breast cancer could be elevated.
The group evaluated data from 15 prospective cohort studies. Compared with women of the same age who had never given birth, women who had given birth had an increased risk for breast cancer that peaked about five years after birth and continued for about 24 years, the researchers found. The increased risk was seen for breast cancers that were positive and negative for the estrogen receptor, and breastfeeding did not modify risk patterns. The risk may be higher depending on the woman's age or if she has a family history of breast cancer.
"Combined with evidence from other studies, this research may help to develop better breast cancer risk prediction models to inform decision-making around breast cancer screening and prevention strategies," according to a statement from the journal.
