Biological and pathological features in pregnancy-associated breast cancer: a matched case-control study

Background: The prognosis for breast cancer has been considered to be worsened by the coexistence of pregnancy. However, to date, significant controversy still exists regarding the pathological tumor features and prognosis of patients diagnosed with pregnancy-associated breast cancer (PABC). The aim of the present study was to analyze the different prognostic factors and outcome in PABC subset versus a non-PABC control group matched for age and year of diagnosis. Materials and Methods: A total of 56 PABC cases were diagnosed from 1990 to 2008, for whom 73 non-PABC patients were identified. Pathological characteristics, immunohistochemical features, and differences in overall and disease-free survival were compared between both groups. Results: Compared to non-PABC controls, PABC patients presented more advanced disease (31% vs 13%, p = 0.024) and greater lymph node involvement (53% vs 34%, p = 0.034). Pathological and tumor features tended to present poorer prognostic factors in the PABC subset. Survival was poorer in the PABC patients (five-year DFS 68% in PABC vs 86% in non-PABC, p = 0.12). However, analysing survival adjusted for stage and age, the authors did not find significant differences between both groups. Conclusions: PABC patients tended to be diagnosed in advanced breast disease and presented tumors with adverse pathological prognostic factors. While the authors found a poorer outcome in PABC group, no significant differences were observed with stage-matched analysis. The present results may suggest that the poorer prognosis observed within PABC women could not be due to pregnancy itself, but with a delay in diagnosis and tumor subtype pathological features.