Abstract P6-16-01: The importance of loco-regional tumor burden and surgery on survival in patients with de novo stage IV breast cancer; post-hoc analyses of protocol MF07-01

Background: The MF07-01 trial is a multicenter phase III randomized controlled trial of treatment naive stage IV BC patients comparing loco-regional surgery (LRS) followed by appropriate systemic therapy (ST) versus ST alone. Aims: To evaluate the importance of loco-regional tumor burden and surgery on overall survival rate in patients with de novo stage IV breast cancer. Methods: At initial diagnosis patients were randomized 1:1 to LRS group or ST group. The surgery was a lumpectomy (L) or mastectomy (M) and sentinel lymph node biopsy (SLNB) ± axillary lymph node dissection (ALND). After surgery all patients received systemic treatment + endocrine treatment (ET) and Trastuzumab based on pathology results. The demographic, pathologic, and clinical characteristics of the patients were recorded. Results: 274 patients were accrued; 138 in the LRS group and 136 in the ST group. The groups were comparable regarding age, BMI, HER2 neu, tumor type and size, histologic grade, and bone and visceral metastasis (all p>0.05). In the LRS group 36 patients (26%) had L+ALND, 92 patients (67%) had M+ALND and 10 patients (7%) had M+SLNB, respectively. The axillary positivity rate was 89.1%. There were 76 (55%) deaths in the LRS group and 101 (74%) in the ST group during the median 40 (20-51) month follow-up. Overall survival (OS) was 34% higher in the LRS group compared to the ST group (HR: 0.66, 95%CI 0.49-0.88: p = 0.005). Overall survival rate was higher in LN (+) (p=0.01), tumor size Conclusion: In this subgroup analysis, we observed that patients with high grade tumor, without skin or chest wall involvement and positive axilla who underwent surgery for primary breast tumor and axilla had better overall survival than ST in de novo stage IV breast. These results can be considered in clinical research design for stratification. Citation Format: Ozmen V, Ozbas S, Karanlik H, Muslumanoglu M, Igci A, Canturk Z, Utkan NZ, Ozaslan C, Evrensel T, Uras C, Aksaz E, Soyder A, Ugurlu UM, Col C, Cabioglu N, Bozkurt B, Sezgin E, Dagoglu T, Uzunkoy A, Dulger M, Koksal N, Cengiz O, Gulluoglu B, Unal B, Atalay C, Yildirim E, Erdem E, Salimoglu S, Sezer A, Koyuncu A, Gurleyik G, Alagol H, Ulufi N, Berberoglu U, Soran A. The importance of loco-regional tumor burden and surgery on survival in patients with de novo stage IV breast cancer; post-hoc analyses of protocol MF07-01 [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-16-01.