Abstract P4-07-01: Overall survival with locoregional surgery in de novo metastatic breast cancer

Abstract Background: Breast cancer remains the most frequent type of cancer in women, with de novo metastatic breast cancer (dnMBC) accounting for approximately 6-10% of patients. Advances in treatment of dnMBC have led to an increase in overall survival (OS), but the role of locoregional surgery remains unclear. Aim: To determine the value of locoregional surgery compared with no surgery on OS of women with dnMBC Settings and design: This study was designed as a randomized clinical study and was approved by the Ethics Committee of the Ethics Committee of Cangzhou Clinical College of Integrated Traditional Chinese and Western Medicine of Hebei Medical University (NO.20200212). Methods: Patient characteristics were previously reported in ASCO2022. Eighty-six patients with dnMBC were randomised to surgery of the primary tumor followed by systemic therapy (surgery group) or to primary systemic therapy without surgery (non-surgery group), by a computer generated block randomisation sequence. Randomisation was stratified by site of distant metastases, number of metastatic lesions, and molecular subtypes. Follow-up visits were conducted during treatment, monthly in first year, every 3 months thereafter. The primary endpoint was overall survival analysed by intention to treat. The stratified log-rank test and Cox proportional hazards model were used to compare OS between groups. The level for significance was set at p< 0.05. All analyses were performed with STATA 17. Results: Between Jan 3, 2019, and Mar 29, 2021, of the 103 women presenting with dnMBC, we randomly assigned 86 patients: 44 to surgery of the primary tumor followed by systemic therapy and 42 to primary systemic therapy without surgery. At data cut-off of Dec 1, 2021, median follow-up was 27 months with 44 deaths (surgery group n=21, non-surgery group n=23). The 2-year OS was 45.2% without and 52.3% with locoregional surgery (hazard ratio=0.59; 95% CI, 0.32 to 1.12; p = 0.11). The median OS was 25.5 months (95% CI, 23.52 to 29.38) in non-surgery group and 33 months (95% CI, 27.43 to 34.53) in surgery group. Conclusions: Our prospective randomized trial showed that compared with non-surgery counterparts, locoregional surgery does not improve OS of patients with dnMBC. Large, well-designed studies involving a large number of cases, multi-institution trials and longer follow-up are needed to verify the finding. Citation Format: Ren Chongxi, Sun Jianna, Kong Lingjun. Overall survival with locoregional surgery in de novo metastatic 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 P4-07-01.