Postmastectomy radiotherapy (PMRT) was associated with improved overall survival (OS) for all pathologic nodal subgroups, according to a study of 15,315 women with breast cancer, including 3,040 with Mast-ypN0, 7,243 with Mast-ypN+, 2,070 with BCS-ypN0, and 2,962 with BCS-ypN+. Researchers found:

• On univariate analysis, PMRT was associated with improved OS for patients with both Mast-ypN0 and Mast-ypN+.

• On multivariate analysis adjusted for factors including age, comorbidity score, cT stage, in-breast pathologically complete response, axillary surgery, ypN stage, estrogen receptor status, and hormone therapy PMRT remained independently associated with improved OS among patients with Mast-ypN0 and Mast-ypN+.

• No differences in OS were seen with the addition of regional nodal irradiation to breast radiotherapy for patients with BCS-ypN0 or BCS-ypN+.

• Propensity-matched scores showed identical patterns of significance.

• On subset analysis, OS was improved with PMRT in each pathologic nodal subgroup (ypN0, ypN1, and ypN2-3).

Citation: Rusthoven CG, Rabinovitch RA, Jones BL, et al. The impact of postmastectomy and regional nodal radiation after neoadjuvant chemotherapy for clinically lymph node positive breast cancer: A National Cancer Database (NCDB) analysis. [Published online ahead of print February 9, 2016]. Ann Oncol. doi: 10.1093/annonc/mdw046.