Abstract P2-14-30: Survival outcomes of breast conserving surgery versus mastectomy for ultrasound detected non-palpable breast cancer in hospital-based screening among Chinese women

Background: Some population-base studies have reported similar or improved survival for breast-conserving surgery (BCS) plus radiotherapy compared with mastectomy (Mx) in early breast cancer [PMID: 22373563, 27344114]. Among the screening detected early breast cancer, ultrasound (US) could detect more invasive non-palpable breast cancer (NPBC) with positive lymph nodes in hospital-based asymptomatic Chinese women, who could achieve comparable 10-year DFS and OS as mammography (MG)-detected NPBC [2016 SABCS P5-02-05, PMID: 27689334]. However, there is little data about the surgical outcomes of BCS verse Mx in the low-risk screening detected NPBC with US as the initial imaging test. Methods: From 2001 to 2017, 6,423 consecutive asymptomatic women underwent mammography or ultrasound guided biopsy in Peking Union Medical College Hospital. Among them, 1130 NPBC including 914 US-detected and 216 MG-detected NPBC were diagnosed and treated. There were 349 (30.9%) patients underwent BCS including 286 (25.3%) patients received radiation therapy and 63 (5.6%) elderly patients (>70 years) who did not. The clinicopathological features, treatment choice, 10-year disease-free survival (DFS) and overall survival (OS) were compared between breast conservingsurgery (BCS) versus mastectomy(Mx) in all NPBC and between the US-detected and MG-detected NPBC. Result: Compared to those who received BCS, the 781 (69.1%) patients who underwent Mx had more cancers with relatively higher histologic grade (p=0.003), positive lymph node (18.8% vs 12.0%, p=0.005), ER-negative (22.5% vs 11.5%, p Conclusion: The 10-year DFS and OS of breast conserving surgery versus mastectomy were similar among all NPBC patients. As the current initial imaging test, US-detected NPBC patients would receive significantly more BCS compared to MG. There was no significant difference in surgical outcomes among BCS and Mx in US-detected NPBC. However, among MG-detected NPBC, patients with Mx reached a better DFS but a similar OS than those with BCS. The radiation therapy could be safely omitted in the elderly patients (>70 years) with NPBC. Citation Format: Yao R, Pan B, Xu Y, Zhou Y, Zhu Q, Zhang J, Wu H, Mao F, Lin Y, Shen S, Sun Q. Survival outcomes of breast conserving surgery versus mastectomy for ultrasound detected non-palpable breast cancer in hospital-based screening among Chinese women [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-14-30.