Abstract P2-14-20: Early locoregional breast surgery improves overall and progression-free survival in oligometastatic breast cancer

Abstract

Abstract Background Four percent of patients have Metastatic Breast Cancer (MBC) at the time of diagnosis. Surgery in this context is generally not recommended. However, tumour resection may have an effect on tumour load influencing metastatic growth. Some studies have suggested an advantage of locoregional surgery in MBC. The objective was to evaluate the effectiveness of surgery in the year following diagnosis of metastatic disease. Methods Data were collected within the ESME breast cancer data platform. Stage IV patients diagnosed between 2008 and 2014 without further personal cancer were included. Patients who died or progressed in 1-year post-diagnosis were excluded. We compared patients operated within the first 12 months after diagnosis with the others. Results Among 1977 patients with MBC at diagnosis, alive and progression-free at 12 months, 530 (26.8%) had surgery within this interval. Patients operated in the year of diagnosis had less oligometastatic disease (less than 3 metastases; 9.2% vs 21.8%, p<0.01) compared to patients with no surgery. They had less bone metastasis (57.7% vs 74.4%, p<0.01), more lymph node (33.2% vs 27.8%, p=0.02), lung (19.8%, p<0.01) and less liver metastasis (17.9% vs 26.8%, p<0.01) sites. Other treatments included more chemotherapy and HER2-targeted therapy (89.1% vs 69.6%, p<0.01), locoregional radiotherapy (81.7% vs 32.5%, p<0.01) and the same frequency of hormone therapy (79.8% vs 78.6%, p=0.57). Multivariate survival analysis based on Cox model showed that surgery of primary breast lesion performed within 12 months (Hazard Ratio(HR)=0.75, p<0.01), HER2 positive status (HR=0.42, p<0.01) and the non-visceral metastases (HR=0.80, p=0.02) improved overall survival (OS) whereas an older age than 50 (HR=1.50, p<0.01) and 3 or more metastases (HR=1.45, p<0.01) were associated with poorer survival. Progression-Free Survival (PFS) was also improved for locoregional surgery (HR=0.70, p<0.001) after adjustment on HER2 positive status (HR=0.70, p<0.01), age greater than 50 (HR=1.18, p<0.01) and 3 or more metastases (HR=1.27, p<0.01). Propensity score matching analyses confirmed these results. Discussion We demonstrated that surgery of primary breast lesion had a benefit on OS (HR=0.75, p<0.01), and PFS (HR=0.70, p<0.01) in metastatic patient. Metastasis number less than 3 was a complementary protective factor to surgery. Studies have sought to evaluate the population that could benefit from surgery of primary breast lesion in the event of metastatic disease. They showed an increasing morbimortality in plurimetastatic patients. In our study, patients with more than 3 metastases had poorer OS and PFS (HR=1.45, p=0.01 and HR=1.27, p=0.03 respectively). Conclusion Results of our study show that surgical control of primary breast lesion could be considered as an option in the locoregional treatment of MBC, particularly in non-visceral oligometastastic breast cancer. Citation Format: Hotton J, Lusque A, Rauch P, Leufflen L, Buhler J, Pierret M, Salleron J, Marchal F. Early locoregional breast surgery improves overall and progression-free survival in oligometastatic breast cancer [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 P2-14-20.