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

While local treatment of metastases is considered to be unrelated to prognosis, previous studies have suggested that local treatment of isolated lung metastases may have positive prognostic impact. We designed this prospective cohort study to investigate the clinical situation and its outcomes. We enrolled patients with fewer than 3 lung nodules suspected of being oligometastases after curative breast cancer surgery. Treatments, including local and systemic therapy, were selected by the physician and patient in consultation. The primary outcome was overall survival (OS); secondary outcomes were the efficacy and the safety of the surgery for lung oligometastases. Between May 2015 and May 2019, 14 patients were enrolled. Resection of lung nodules (metastasectomy) was performed in 11 (78.6%) of 14 patients, and one of these cases was diagnosed as primary lung cancer. Metastasectomies were all performed employing video-assisted thoracic surgery (VATS) without perioperative complications. Systemic therapies were administered to all patients except one. The respective 3-year and 5-year OS rates of patients with lung oligometastases were 91.6% and 81.5%, respectively. Progression occurred in 6 patients: 3 of the 10 with metastasectomy and all 3 without this surgical procedure. Lung metastasectomy was worthwhile as a diagnostic evaluation and may provide long-term benefit in some patients.