The Role of Postoperative Radiotherapy After Primary Tumor Resection in Patients With De Novo Stage Iv Breast Cancer

Abstract Background: To investigate the role of postoperative radiotherapy (PORT) in stage IV breast cancer patients who underwent planned primary tumor resection (PTR).Methods: This study enrolled 112 patients diagnosed with de novo stage IV breast cancer who were treated with potentially curative PTR with or without PORT. The primary outcome was overall survival (OS), and the secondary outcomes were locoregional recurrence-free survival (LRRFS) and distant progression-free survival (DPFS).Results: At a median follow-up of 48.9 months (range, 3.5–183.4 months), the median OS was 54.9 months (range, 5.3–185.9 months) with a 5 year OS rate of 59.6%. Luminal A or B type tumors and PORT were significantly predictive of longer OS. The 5 year LRRFS and DMFS rates were 79.0% and 34.3%, respectively. PORT was the only significant predictor of LRRFS (hazard ratio [HR], 0.36; 95% confidence interval [CI], 0.15–0.86; p = 0.021). A comparison of patients who did and did not receive PORT showed that patients with disseminated metastasis more likely did not receive PORT and were excluded from the analysis. Multivariate analysis showed that PORT was significantly predictive of LRRFS (HR, 0.31; 95% CI, 0.11–0.91; p = 0.033) but not of OS. Conclusions: De novo stage IV breast cancer patients who received planned PTR showed favorable survival outcomes compared with historical cohorts. PTR may be predictive of a good prognosis, especially in patients with luminal A or B type tumors. PORT was significantly predictive of LRRFS, suggesting that patients may benefit from this treatment.Trial registration: The present study was not registered due to its retrospective nature.