Clinical features and prognostic factors for extracranial oligometastatic breast cancer in China.

Evidence of an oligometastatic state in metastatic breast cancer (MBC) is relatively limited. The aim of our study was to investigate the clinical features and prognostic factors for extracranial oligometastatic breast cancer and to identify the best treatment approaches in this select population. Fifty postoperative inpatients diagnosed with extracranial oligometastatic breast cancer at the National Cancer Center in China between 2009 and 2014 were consecutively enrolled. Oligometastatic breast cancer was defined as MBC with three or fewer metastatic lesions confined to one organ; de novo Stage IV disease and local-regional recurrence were excluded. The median progression-free survival (PFS) and overall survival (OS) times were 15.2 and 78.9 months, respectively, and the 2-year PFS and 5-year OS rates were 40% and 58%, respectively. First-line treatment approach with standard systemic treatment + surgical resection for all metastatic lesions was an independent prognostic factor for prolonged PFS (hazard ratio = 0.32; 95% confidence interval [CI], 0.14-0.73; P = .006) and OS (hazard ratio = 0.35; 95% CI, 0.14-0.86; P = .022). Subgroup analysis showed that patients with a disease-free interval (DFI) ≥24 months, one metastatic lesion or the hormone receptor (HR) + subtype were more likely to get benefit from resection. Patients with oligometastatic breast cancer have a relatively good prognosis. Surgical resection for metastatic lesions could significantly improve PFS and OS. Further prospective research is warranted to confirm the results and to develop biomarkers for better patient selection.