background • Pregnancy-associated breast cancer (PABC) is defined as breast cancer diagnosed during pregnancy and within one year after delivery. PABC is a challenging and complex case for patients and their physicians. Pregnancy and lactation produce anatomical and physiological changes in breast tissue which make diagnosis of breast masses more difficult. Many studies conclude that PABC have more adverse prognosis than non-PABC. Our study aims to determine the prognostic factors in PABC then compare them with nonPABC.

Methods• A retrospective case-control study at Albaironi University hospital in Damascus. the study included 50 patients identified with PABC between 2005 and 2015. then we selected 100 patients (2:1) identified as non-PABC between 2010 and 2015. the differences in clinical features and prognostic factors were compared between cases and controls. Results • Of the 50 PABC cases, breast cancer was diagnosed during pregnancy in 22 patients, and within one year after delivery in 28 patients. PABC cases were more likely than controls to be negative for estrogen receptor (41% vs 14%, p = 0.03) and negative for progesterone receptor (50% vs 21%, p = 0.04) and they were more likely than controls to be triple negative (21% vs 5%, p = 0.02). Cases were also more likely to have advanced stage (p = 0.03), and were more likely to have a metastasis (M1) at diagnosis (27% vs 8%; p = 0.01).

Conclusion • Pregnancy-associated breast cancer is a clinically and biologically distinct entity. PABC is associated with more adverse tumor features and prognostic factors than non-PABC matched for age.

Keywords: breast cancer; pregnancy; prognostic factors