Oligometastasis of Breast Cancer to the Lung: Prospective Cohort Study of Treatment Strategies (SBP-06)

Abstract BackgroundPrevious study results have suggested that local treatment of isolated lung metastases, may be beneficial and increase overall survival (OS) in highly selected patients. However, these were all retrospective studies. We designed this prospective cohort study to investigate the therapeutic and diagnostic clinical situation of oligometastatic breast cancer in the lung, as well as the prognosis outcomes of patients with this disease.MethodsWe enrolled patients with less than 3 lung nodules which suspected as oligometastases after curative breast cancer surgery. Treatments, including local and systemic therapy, were choice by each physician. The primary outcome was OS of patients with oligometastasis of breast cancer detected in the lung and secondary outcomes were the efficacy and safety of surgery for lung oligometastases. The study was in accordance with the relevant national/institutional guidelinesResultsBetween May 2015 and May 2019, 14 patients were enrolled at 5 centers. Resection of lung nodules (metastasectomy) was performed 11 (78.6%) of 14 patients and one was diagnosed with primary lung cancer. Metastasectomy were all performed employing video-assisted thoracic surgery (VATS) and achieved complete resection without perioperative complication. Systemic therapies such as chemotherapy, as well as endocrine and molecular target therapies were administered to all patients except one who declined all treatments offered. The respective 3-year and 5-year OS rates of patients with lung oligometastases were 91.6% and 81.5%. Progression events occurred in 6 patients: 3 (30%) with and 3 (100%) without metastasectomy. Whereas 2 of 10 patients with metastasectomy survived 5 years without progression, progression events occurred all patients without metastasectomy within 1 year.ConclusionLung metastasectomy was worthwhile as a diagnostic evaluation and possibly provide long-term benefit in some patients. Phase 3 trials might be required to provide definitive evidence and to provide criteria for selecting patients. Trial registrationThis study was approved by the Institutional Review Board (IRB No. 960) of the Okayama University Hospital, Okayama, Japan, and was registered in the clinical trials database UMIN (UMIN000016999) on 31 March 2015. Written informed consent was obtained from all enrolled patients.