Pregnancy did not negatively affect survival among women with breast cancer, according to results of a population-based cohort study.
Researchers reported a higher 5-year OS rate among women who became pregnant 6 months or more after breast cancer diagnosis than among women who did not become pregnant.
“We were surprised that pregnancy after breast cancer seemed to reduce the risk of the cancer coming back,” Steven A. Narod, MD, FRCPC, senior scientist at Women’s College Research Institute at University of Toronto, told HemOnc Today. “However, we need to confirm this.”
About 247,000 women in the United States were diagnosed with breast cancer last year. Women younger than 45 years accounted for 26,392 (10.7%) of these cases.
Given the trend of women delaying motherhood, the proportion women who develop breast cancer while pregnant is increasing. However, chemotherapy is not recommended during the first trimester in order to maintain the health of the mother and fetus. Radiotherapy and hormonal therapies are not recommended at any time during pregnancy.
Narod and colleagues used the Ontario Cancer Registry to identify 7,553 women aged 20 to 45 years (median age, 40 years) diagnosed with invasive breast cancer from 2003 to 2014. Researchers compared OS between women diagnosed during pregnancy or in the postpartum period with those who did not become pregnant.
More than three-quarters of women (77.2%; n = 5,832) had no pregnancy, meaning they did not conceive a child from 5 years before to 5 years after diagnosis; 14.7% had pregnancy before breast cancer (conception from 5 years to 1 year before diagnosis; n = 1,108); 6.6% had pregnancy-associated breast cancer (conception from 11 months before until…