Pregnancy-associated breast cancer: a multicenter study comparing clinicopathological factors, diagnosis and treatment outcomes with non-pregnant patients.

Purpose: Pregnancy-associated breast cancer (PABC), defined as breast carcinoma diagnosed during pregnancy or in the first post-partum year, is one of the most common gestation-related malignancies with reported differences in tumor characteristics and outcomes. This multicenter study aims to review cases of PABC in Singapore, including their clinicopathological features, treatment, and clinical outcomes compared to non-PABC patients.

Methods: Demographic, histopathologic and clinical outcomes of 93 PABC patients obtained from our database were compared to 1424 non-PABC patients.

Results: PABC patients presented at a younger age. They had higher tumor and nodal stages, higher tumor grade, were more likely to be hormone receptor negative and had a higher incidence of multicentric and multifocal tumors. Histological examination after definitive surgery showed no significant difference in tumor size and number of positive lymph nodes suggesting similar neoadjuvant treatment effects. Despite this, PABC patients had worse outcomes with poorer overall survival and disease-free survival, OS (P < 0.0001) and DFS (P < 0.0001). Termination of pregnancy did not improve survival.

Conclusion: Patients with PABC present at a higher stage with more aggressive disease and have poorer outcomes compared to non-PABC patients. Reducing delay in diagnosis and treatment may help improve survival.