Pregnancy associated breast cancer (PABC): Report from a gestational cancer registry from a tertiary cancer care centre, India.

Abstract Background Pregnancy associated breast cancer (PABC) is a rare entity and defined as breast cancer diagnosed during pregnancy or one-year post-partum. There is sparse data especially from low and middle-income countries (LMIC) and merits exploration. Methods The study (2013 -2020) evaluated demographics, treatment patterns and outcomes of PABC. Results There were 104 patients, median age of 31 years; 43 (41%) had triple-negative disease, 31(29.8%) had hormone-receptor (HR) positive and HER2 negative, 14 (13.5%) had HER2-positive and HR negative and 16(15.4%) had triple positive disease. 101(97%) had IDC grade III tumors and 74% had delayed diagnosis. 72% presented with early stage (24, EBC) or locally advanced breast cancer (53, LABC) and received either neoadjuvant (n=49) or adjuvant (n=26) chemotherapy and surgery. Trastuzumab, tamoxifen, and radiotherapy were administered post-delivery. At a median follow up of 27 (IQR:19-35) months, the estimated 3-year event-free survival (EFS) for EBC and LABC was 82% (95% CI: 65.2 – 100) and 56% (95% CI: 42 - 75.6%) and for metastatic 24% (95% CI: 10.1% - 58.5%) respectively. Of the 104 patients, 34 were diagnosed antepartum (AP) and 15 had termination, 2 had preterm and 16 had full-term deliveries(FTDs). Among postpartum cohort (n=70), 2 had termination, 1 had preterm, 67 had FTDs. 83(including 17 from AP) children from both cohorts were experiencing normal milestones. Conclusion Data from the first Indian PABC registry showed that the majority had delayed diagnosis and aggressive features(TNBC, higher grade). Treatment was feasible in majority and stage matched outcomes were comparable to non-PABCs.