UCLA

BACKGROUND: After treatment of pregnancy-associated breast cancer (PABC), some women desire future pregnancy. While safety of pregnancy after breast cancer has been demonstrated, the same cannot be said about women with PABC. OBJECTIVE: The aim of this study was to describe the incidence and outcomes of patients with PABC with subsequent pregnancies compared with those without another pregnancy. METHODS: A retrospective chart review identified patients diagnosed with breast cancer during pregnancy or within 5 years postpartum between 2011 and 2023. Patients were then screened for further pregnancy. Clinicopathologic variables, oncologic outcomes, and pregnancy outcomes were recorded. The Chi-square test and t-test were used to compare patients with subsequent pregnancy with those without. Kaplan-Meier method and log-rank test were used to estimate 5-year disease-free survival (DFS). RESULTS: Overall, 75 patients with PABC were identified, 58 of whom had PABC and no further pregnancies (NSP-PABC) and 17 with subsequent pregnancy (SP-PABC). Compared with patients with NSP-PABC, patients with SP-PABC were significantly younger (p = 0.015) and less likely to have prior pregnancies (p < 0.001). Overall median follow-up was 4.3 years. Calculated 5-year DFS rates were 86.2% and 89.0% for the SP-PABC and NSP-PABC groups, respectively (p = 0.76). Calculated 5-year overall survival was 100% and 90.7% for the SP-PABC and NSP-PABC groups, respectively (p = 0.22). Within the SP-PABC group, 14/17 patients had successful deliveries. CONCLUSIONS: This study provides the first descriptions of patients with PABC and subsequent pregnancy. Additional investigation, likely with pooled analysis from multiple institutions, is necessary to determine the oncologic and obstetric safety of pregnancy following PABC.