Abstract P1-20-11: Surgical intervention improves survival in patients with de novo metastatic breast cancer: A population-based analysis
Authors: Feng Zhe , Chen Xinyu , Zhang Jian , Tao Zhonghua , Hu Xichun 
Published: March 2020

Abstract
Background Although impact of surgery on survival for de novo metastatic breast cancer (MBC) patients has been debated for decades, it remains controversial. We sought to evaluate whether surgery of primary site (SPS) and surgery of metastatic site (SMS) provide survival benefits in a large cohort. Methods A retrospective population-based cohort study was conducted by using data from the 2010-2015 Surveillance, Epidemiology, and End Results (SEER) program. Descriptive statistical analysis was used to compare demographic, tumorous and therapeutic characteristics. Median survival was estimated by Kaplan-Meier method. Cox regression models were used to assess risk of breast cancer related death and all-cause death between de novo MBC patients who underwent SPS or SMS and who did not. To minimize selection bias, we conducted additional analysis in patients who were recommended to SPS. Nomograms were constructed based on the Cox regression model to predict 3-year overall survival (OS) and breast cancer specific survival (BCSS) for patients who were recommended to SPS. The nomograms were further internal validated and assessed by calibration curves. Results There were 12443 patients eligible for the study, of whom 4482 patients were recommended to SPS and 3869 patients ultimately performed SPS. Median BCSS and OS of patients were longer in SPS group than non-SPS group, both in the entire population (49.00 vs. 27.00months, P&lt;0.001; 43.00 vs. 23.00 months, P&lt;0.001) and patients who were recommended to SPS (49.00 vs. 30.00 months, P&lt;0.001; 43.00 vs. 27.00 months, P&lt;0.001). Multivariate Cox regression analysis revealed SPS was an independent prognostic factor for BCSS (HR 0.567, 95% CI 0.532-0.604, P&lt;0.001) and OS (HR 0.568, 95% CI 0.535-0.603, P&lt;0.001) in de novo MBC patients. For patients recommended to SPS, prognosis was also more favorable in SPS group (HR 0.742, 95%CI 0.648-0.849, P&lt;0.001 for BCSS; HR 0.756, 95%CI 0.666-0.859, P&lt;0.001 for OS). Nomograms showed molecular subtype and metastatic pattern contributed the most to prognosis in patients recommended to SPS. Subgroup analysis in patients recommended to SPS showed that SPS didn’t reduce risk of death in patients with triple negative breast cancer (TNBC) (BCSS HR 1.035, 95% CI 0.771-1.389, P= 0.820; OS HR 1.057, 95% CI 0.798-1.400, P=0.700), synchronous lung and liver metastases (BCSS HR 0.982, 95% CI 0.603-1.599, P=0.942; OS HR 0.975, 95% CI 0.618-1.539, P=0.914), or central nervous system (CNS) metastasis (BCSS HR 0.709, 95% CI 0.427-1.179, P=0.185; OS HR 0.876, 95% CI 0.531-1.444, P=0.603). Of 12437 patients who had complete records on SMS, 783 (6.30%) patients underwent SMS. Median BCSS and OS of patients in SMS group were longer than non-SMS group (43.00 vs. 32.00 months, P&lt;0.001; 38.00 vs. 28.00 months, P&lt;0.001). SMS was also an independent prognostic factor for BCSS (HR 0.734, 95% CI 0.652-0.827, P&lt;0.001) and OS (HR 0.761, 95% CI 0.682-0.849, P&lt;0.001) in de novo MBC patients. Subgroup analysis indicated that patients with hormone receptor (HR) negative/ human epidermal growth factor receptor 2 (HER2) positive MBC (BCSS HR=0.853, 95%CI 0.558-1.303, P=0.461; OS HR=0.846, 95%CI 0.564-1.270, P=0.421), TNBC (BCSS HR=0.782, 95%CI 0.613-0.996, P=0.046; OS HR=0.820, 95%CI 0.656-1.025, P=0.082) or non-visceral metastasis (BCSS HR=1.039, 95%CI 0.717-1.505, P=0.840; OS HR=1.009, 95%CI 0.711-1.431, P=0.960) might not benefit from SMS. Conclusions SPS and SMS were associated with survival benefit for de novo MBC patients. However, SPS and SMS should be cautiously performed in selected de novo MBC patients after comprehensive assessment especially including breast cancer subtype and metastatic pattern.
Citation Format: Zhe Feng, Xinyu Chen, Jian Zhang, Zhonghua Tao, Xichun Hu. Surgical intervention improves survival in patients with de novo metastatic breast cancer: A population-based analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-20-11.