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.

Background: In an earlier analysis of this cohort study, local therapy based on surgical resection of the primary tumor might confer a survival benefit in women with de novo metastatic breast cancer (dnMBC). Here we report the survival outcomes of locoregional treatment (LRT), focusing on the association of surgical timings and surgical margins with survival in these patients. Methods: The retrospective study included patients with dnMBC in two Chinese tertiary hospitals, between March 1, 2007, and December 31, 2017. Overall survival (OS) was evaluated by means of a stratified log-rank test and summarized with the use of Kaplan–Meier methods. Results: A total of 153 patients were included, of whom 87 underwent LRT and 66 systemic therapy alone (STA). LRT showed a significant OS benefit over STA (HR, 0.47; 95% CI, 0.33 to 0.69; p<.0001). Median OS of LRT group and STA group were 42 months (95% CI, 35.0 to 48.9 months) and 21 months (95% CI, 16.1 to 25.9 months), respectively. The benefit was consistent across most subgroups. The OS of patients undergoing surgery was better than that of patients without surgery (HR, 0.48; 95% CI, 0.33 to 0.70; p=.0001), and there was difference in survival improvement at different surgical timings (surgery before chemotherapy, during chemotherapy and after chemotherapy) (HR, 0.79; 95% CI, 0.65 to 0.95; p=.013). The survival benefit of surgery after chemotherapy was the most, followed by surgery during chemotherapy (Median 56 months, 95% CI, 40.8 to 71.2 months). Moreover, compared with patients with positive margins, the OS of patients with negative margins was significantly improved (HR, 2.35; 95% CI, 1.65 to 3.35; p<.0001), with a median OS of 56 months (95% CI, 45.9 to 66.1 months). Conclusions: Our results suggest that LRT is associated with improved OS in women with dnMBC, and patients who had surgery after or during systemic chemotherapy with negative surgical margins, are expected to benefit more.

e13044 Background: Breast cancer remains the most frequent type of cancer in women, with de novo metastatic breast cancer (dnMBC) accounting for approximately 10% of patients. Advances in diagnosis and treatment of breast cancer have led to an increase in cancer survival, resulting in quality of life (QoL) improvement. However, there are few reports on whether local treatment improves quality of life for de novo metastatic breast cancer (dnMBC). Aim: To evaluate QoL in dnMBC patients since randomization using scores from the FACT-B health survey. Settings and design: This study was designed as a prospective observational research project 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: 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). QoL analyses covering the results at baseline, 6,12,18,24 and 30 months follow up of 81 (94%) patients, was assessed with the Functional Assessment of Chronic Illness Therapy General Questionnaire, including Breast Cancer Supplement (FACT-B) questionnaires. Inclusion criteria were: did not meet the diagnostic criteria of de novo metastatic breast cancer and patients could not cooperate QoL was assessed by FACT-BTOI variables evaluated at 6 time point. Average FACT-B TOI score was measured by the prorated aggregate score of 37 items from the FACT-B. The Wilcoxon rank sum test was used to compare the differences at each time point. The level for significance was set at p<0.05.All analyses were performed with STATA 16. Results: From 2019 to 2021,a total of 86 dnMBC patients were selected and recruited in Department of breast surgery of our hospitals. Among them, 81 completed FACT-B questionnaires and their data were analyzed. Forty-one (95%) patients in the surgery group and 40 (93%) in the non-surgery group were included in the QoL analyses. A total of 362 QoL questionnaires were analyzed, 81(100%) at baseline, and 73(90%), 64(79%), 58(72%), 47(58%), 39(48%) at 6,12,18,24, and 30 months, respectively. The average FACT-B TOI scores showed no statistically significant difference between the two groups at each time point, with a P value of 0.09 at baseline, and 0.47,0.67,0.36,0.45,0.34 at 6,12,18,24, and 30 months, respectively. No significant difference was found in QOL evaluation between the two groups. Conclusions: Our prospective randomized trial showed that compared with non-surgery counterparts, locoregional surgery does not improve QoL of patients with dnMBC. Clinical trial information: 20200212.

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