Clinicopathological features and prognosis of patients with pregnancy-associated breast cancer: A matched case control study.

Aim We aimed to clarify tumor features and prognosis of pregnancy-associated breast cancer (PABC) among Chinese women. Methods PABC was defined as breast cancer diagnosed during pregnancy or within a year after delivery. Patients with PABC were selected from breast cancer cases of women ≤45 years treated at our institution between December 2012 and December 2017, and one non-PABC control was matched for stage, age, and year of diagnosis for each case. Results Forty-one women with PABC were identified (22 diagnosed during pregnancy and 19 within 1 year of delivery). There were significantly more progesterone receptor (PR)- and triple-negative tumors in the PABC (56.1% and 24.4%, respectively) than in the non-PABC group (31.7% and 4.9%, respectively) (P = .045 and .026, respectively). Human epidermal growth factor receptor 2 positivity was the same in both groups (31.7%). Median disease-free survival (DFS) was 29.0 months (95% confidence interval [CI], 6.5-51.5 months) in the PABC and 40.9 months (95% CI, 22.8-58.8 months) in the non-PABC group (P = .167). Median overall survival (OS) was 82.8 months in the PABC (95% CI, 39.3-126.5 months) versus 80.1 months (95% CI, 56.7-103.6 months) in the non-PABC group (P = .131). Conclusion Histological features were similar in both groups, except that PR- and triple-negative tumors were more frequent in the PABC group. Survival analyses show similar OS for patients with PABC and non-PABC. DFS tended to be shorter in the PABC group; however, this difference was not statistically significant.