Surgery of the Primary Tumor for De Novo Metastatic Breast Cancer: the Controversy Continues

Background: De novo metastatic breast cancer (dnMBC) represents 6–10% of breast cancer. Due to its incurability, dnMBC is generally treated with systemic therapies to achieve disease control and reduce tumor-related symptoms. The need for radical loco-regional treatment and its consequent benefit in this setting remains still controversial. Meta-analysis of retrospective studies and prospective randomized studies did not report a clear survival benefit. The aim of this study was to analyze the impact of surgery to primary tumor (PT) in patients (pts) presenting with dnMBC. Methods: Between Feb 2006-Oct 2015 we performed a retrospective chart review to 129 consecutive pts who attended our hospital with dnMBC. Descriptive, Kaplan-Meier and Cox regression analyses were carried out using SPSS version 23.0. Results: A total of 129 pts. were analyzed. Median age was 68 years (range: 20-95), 59 pts (46%) had single organ metastasis, and their distribution according to the predominant site of disease was: skin/soft tissue 42 pts (33%), bone 87 pts (67%) and visceral 85 pts (66%). Surgery (S) of the PT was done in 32 pts (25%), 24 was radical procedures, 8 palliative and besides, 27 pts underwent axillary dissection. Initial S treatment was the choice for 29 pts. In the S group single organ disease was present in 66% vs 39% non-S group. Metastatic sites were: 50% vs 71% visceral, 44% vs 21% with bone metastasis in the S vs non-S group respectively. With a median follow-up of 2 years (SD 2.20), the 5-yr overall survival (OS) was 11.64% in the entire de novo MBC population, with a median OS of 36 m in the S-group vs 21 m. in the non-S-group (HR 1.46 p = 0.081). Subgroup analyses did not show a benefit of PT surgery in OS regardless of the number of metastasis and site of disease, and BC subtypes. The multi-adjusted HR for surgery was 0.14 (p = 0.188). The multivariate Cox regression analysis model included the site of disease (p = 0.971), the histopathologic grade (p = 0.876) and the hormone receptor status (p = 0.003). Conclusions: In our series, surgical treatment of the primary tumor in patients with de novo metastatic breast cancer did not show a benefit in overall survival. Results of ongoing randomized trials are needed. Legal entity responsible for the study: Medical Oncology Service, Basurto University Hospital. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.