Impact Of Postmastectomy Radiation Therapy On Locoregional Recurrence For Breast Cancer Patients With 1 To 3 Positive Lymph Nodes In The Modern Treatment Era.

1046Background: Clinical guidelines recommend strong consideration of postmastectomy radiation therapy (PMRT) for breast cancer patients with 1 to 3 positive axillary lymph nodes. However, given modern treatment strategies, controversy remains regarding whether PMRT is necessary for these patients. Our aim was to assess the significance of PMRT in the modern era for patients (2006-2012) with 1 to 3 positive lymph nodes by using propensity score matching. Methods: We identified 391 breast cancer patients with 1 to 3 positive lymph nodes who were treated with mastectomy and axillary lymph node (ALN) dissection between 1998 and 2012. Propensity score weighting was used to minimize the influence of confounding factors between the PMRT and no-PMRT groups. Results: The median follow-up time was 6.5 years. In the modern treatment era, no significant difference in locoregional recurrence (LRR)-free survival was noted between the PMRT and no-PMRT groups (P = 0.3921). The 8-year LRR-free survival rates of the PMRT ...