380PClinico-pathological features and prognosis of patients with pregnancy associated breast cancer: A matched case control study

Abstract Background The impact of pregnancy on clinico-pathological features and prognosis of breast cancer remains controversial.We aimed to evaluate the impact of the association of pregnancy with breast cancer on tumor feature and prognosis- overall survival (OS) and disease free survival (DFS). Methods We defined Pregnancy Associated Breast Cancer (PABC) as breast cancer diagnosed during pregnancy or within a year following delivery. We enrolled PABC patients(pts) treated at our institution between December 2012 and December 2017 , and for each case, one non-PABC control was matched for stage, age, and year of diagnosis. Chis-quare and Fisher’s exact test, the Kaplan-Meier method, and Cox’s regression model were used. Univariate and multivariate analyses were performed to assess the parameters associated with prognosis. Results 41 women with PABC were identified; 22 pts were diagnosed during pregnancy and 19 were diagnosed within one year of postpartum. There were more PR negative and triple negative tumors in the PABC(56.1% and 24.4%) than in the non-PABC(31.7% and 4.9%) (p = 0.045 and 0.026 respectively). The HER2 positivity was the same in the two group, both 31.7%. Median DFS in PABC pts was 29.0 months (95% CI range 6.5-51.5 months ) compared with 40.9 months (95% CI range 22.8–58.8 months) in the non-PABC pts(p = 0.167). Median OS in two groups were similar and even longer in PABC group, 82.8 months in PABC pts range(95% CI 39.3-126.5months) compared with 80.1 months (95% CI range 56.7-103.6months) in the non-PABC pts( p = 0.131). Conclusions The results show histological features were similar in both groups, except that triple-negative tumors were more common in the PABC group. The survival analyses show similar OS for patients diagnosed with PABC compared with non-PABC patients, and DFS tends to be shorter for PABC but no significant difference was observed. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.