This retrospective matched cohort study aimed to compare survival outcomes between HER2-positive pregnancy-associated breast cancer (PABC) patients and non-PABC patients in Jordan.

A total of 126 HER2-positive patients (63 PABC, 63 matched non-PABC) were analyzed using data from a single tertiary cancer center between April 2006 and January 2021. Matching criteria included age, histopathology, and clinical stage. Outcomes assessed were overall survival (OS) and recurrence-free survival (RFS). Additional analyses examined treatment timing and completion. Survival was evaluated using Kaplan-Meier estimates and log-rank tests.

Overall survival did not differ significantly between PABC and non-PABC groups (p = 0.12), although a clinically meaningful trend toward lower 5-year OS in the PABC group was observed (68% vs. 83%, p = 0.051). RFS was significantly worse in the PABC cohort (p = 0.026), particularly among postpartum breast cancer (PPBC) patients. PABC patients experienced notable delays in initiating anti-HER2 therapy compared to non-PABC patients (mean 21.3 weeks vs. 16.9 weeks, p = 0.02). Completion of anti-HER2 therapy strongly correlated with improved OS and RFS compared to incomplete or no treatment (p = 0.004 and p = 0.02, respectively).

Timely initiation and completion of anti-HER2 therapy are essential to optimize outcomes in HER2-positive PABC patients. Despite treatment delays, overall survival was maintained when therapy was completed, highlighting the importance of sustained access to multidisciplinary care during and after pregnancy.