Is Pregnancy Safe in Patients with BRCA-Mutant Breast Cancer?

Reports have been limited regarding the success and safety of later pregnancy in carriers of BRCA1/2 mutations who developed breast cancer and completed therapy. Now, researchers in a consortium of 78 centers around the world have collaborated to identify patients aged 40 years or younger who had completed breast cancer treatment and who had germline pathogenic BRCA1 or BRCA2 mutations or both.

This retrospective cohort study identified 4732 eligible patients over a 20-year period with a median follow-up of 7.8 years (median patient age, 35; interquartile range, 31–38). Patients who got pregnant, compared with those who did not, were significantly more likely to be younger at cancer diagnosis, to have node-negative and hormone receptor (HR)–negative disease, to have BRCA1 mutations, and to have received ovarian suppression. At 10 years, the cumulative incidence of pregnancy, a coprimary study endpoint, was 22% (HR-negative; 26%; HR-positive, 18%). The median time from breast cancer diagnosis to pregnancy was 3.5 years (HR-positive, 4.3 years; HR-negative, 3.2 years); pregnant patients' median age was 34.7 years. Pregnancy went to term in 80% of patients. Fewer than 1% of pregnancies were associated with any congenital abnormality.

There was no significant association between pregnancy and disease-free survival (DFS), the other coprimary endpoint. Subgroup analyses suggested that pregnancy was associated with more DFS events in women carrying BRCA2 mutations (hazard ratio, 1.55) but not in BRCA1 carriers.