Abstract P6-05-59: Clinical Characteristics and Prognosis of Postpartum Breast Cancer

Abstract

Abstract Background: Postpartum breast cancer (PPBC) is a not well-established subset of breast cancer, and only few studies address its poorer prognosis. However, there are previous studies that PPBC is associated with worse outcome with higher rates of metastasis than in young women’s breast cancer (YWBC). The purpose of this study was to analyze the clinical characteristics and prognosis according to the onset period of PPBC, Materials and methods: 208,780 breast cancer patients from the online Korean Breast Cancer Society (KBCS) registry database between January 2000 and December 2014 were reviewed retrospectively. Premenopausal women aged 20 to 50 years who underwent breast cancer surgery were included. According to the diagnosis period of breast cancer, it was classified into groups diagnosed within 5 years (PPBC< 5) after delivery, between 5-10 years((5≤PPBC< 10), and after 10 years(PPBC≥10). Results: The patients in PPBC < 5 group showed a younger and more advanced stage compared to other groups, and the expression of estrogen receptor (ER) and progesterone receptor (PR) was lower and the HER2 positive rate was higher. PPBC< 5 group had worse survival rate compared to nulliparous and other group (5-year cumulative survival; PPBC< 5 group, 89% vs. nulliparous group, 97.3% vs. 5≤ PPBC< 10 group 93%). In multivariate analysis, PPBC< 5 group was associated with worse survival rate (Hazard ratio 1.55, 95% CI 1.148-2.094, p=0.004) after adjustment for age at diagnosis, breast cancer stage, ER and HER2 status, Ki-67 level, and chemotherapy. Conclusion: We demonstrated that patients with breast cancer diagnosed within first five years after delivery had aggressive characteristics and a worse survival rate. In order to improve the survival rate of PPBC, the cause should be identified and new therapeutic strategy should be established. Citation Format: Soo Youn Bae, Pill Sun Paik, Young Joo Lee, Young-Joon Kang. Clinical Characteristics and Prognosis of Postpartum Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-05-59.