Background::Pregnancy-associated breast cancer (PABC) is a special type of breast cancer that occurs during pregnancy and within 1 year after childbirth. With the rapid social development and the adjustment of reproductive policies in China, the average age of females at first childbirth is increasing, which is expected to lead to an increase in the incidence of PABC. This study aimed to accumulate clinical experience and to investigate and summarize the prevalence, diagnosis, and treatment of PABC based on large multicenter samples in China.Methods::According to the Chinese Society of Breast Surgery, a total of 164 patients with PABC in 27 hospitals from January 2016 to December 2018 were identified. The pregnancy status, clinicopathological features, comprehensive treatment methods, and outcomes were retrospectively analyzed. Survival curves were plotted using the Kaplan-Meier method.Results::A total of 164 patients of PABC accounted for 0.30% of the total number of cases in the same period; of which, 83 patients were diagnosed during pregnancy and 81 patients during lactation. The median age of PABC was 33 years (24-47 years). Stage I patients accounted for 9.1% (15/164), stage II 54.9% (90/164), stage III 24.4% (40/164), and stage IV 2.4% (4/164). About 9.1% (15/164) of patients were luminal A. Luminal B patients accounted the most (43.3% [71/164]). About 15.2% (25/164) of patients were human epidermal growth factor receptor 2 (Her-2) overexpression and 18.9% (31/164) of patients were triple-negative breast cancer. For pregnancy breast cancer, 36.1% (30/83) of patients received direct surgery and 20.5% (17/83) received chemotherapy during pregnancy. About 31.3% (26/83) chose abortion or induction of labor. The median follow-up time was 36 months (3-59 months); 11.0% (18/164) patients had local recurrence or distant metastasis and 3.0% (5/164) died.Conclusions::It is safe and feasible to standardize surgery and chemotherapy for PABC.“,”Background::Pregnancy-associated breast cancer (PABC) is a special type of breast cancer that occurs during pregnancy and within 1 year after childbirth. With the rapid social development and the adjustment of reproductive policies in China, the average age of females at first childbirth is increasing, which is expected to lead to an increase in the incidence of PABC. This study aimed to accumulate clinical experience and to investigate and summarize the prevalence, diagnosis, and treatment of PABC based on large multicenter samples in China.Methods::According to the Chinese Society of Breast Surgery, a total of 164 patients with PABC in 27 hospitals from January 2016 to December 2018 were identified. The pregnancy status, clinicopathological features, comprehensive treatment methods, and outcomes were retrospectively analyzed. Survival curves were plotted using the Kaplan-Meier method.Results::A total of 164 patients of PABC accounted for 0.30% of the total number of cases in the same period; of which, 83 patients were diagnosed during pregnancy and 81 patients during lactation. The median age of PABC was 33 years (24-47 years). Stage I patients accounted for 9.1% (15/164), stage II 54.9% (90/164), stage III 24.4% (40/164), and stage IV 2.4% (4/164). About 9.1% (15/164) of patients were luminal A. Luminal B patients accounted the most (43.3% [71/164]). About 15.2% (25/164) of patients were human epidermal growth factor receptor 2 (Her-2) overexpression and 18.9% (31/164) of patients were triple-negative breast cancer. For pregnancy breast cancer, 36.1% (30/83) of patients received direct surgery and 20.5% (17/83) received chemotherapy during pregnancy. About 31.3% (26/83) chose abortion or induction of labor. The median follow-up time was 36 months (3-59 months); 11.0% (18/164) patients had local recurrence or distant metastasis and 3.0% (5/164) died.Conclusions::It is safe and feasible to standardize surgery and chemotherapy for PABC.