Postmastectomy Radiation Therapy Based on Pathologic Nodal Status in Clinical Node-Positive Stage II to III Breast Cancer Treated with Neoadjuvant Chemotherapy

Int J Radiat Oncol Biol Phys. 2020 Nov 15;108(4):1030-1039. doi: 10.1016/j.ijrobp.2020.06.028. Epub 2020 Jun 23.


Purpose: The present study aimed to evaluate the effect of postmastectomy radiation therapy (PMRT) after neoadjuvant chemotherapy in patients with node-positive stage II to III (cT1-4N1-2M0) breast cancer.

Methods and materials: A total of 1813 patients from 12 institutions were retrospectively reviewed. Patients were classified into 1 of 3 groups based on the pathologic lymph node status after neoadjuvant chemotherapy: ypN0, ypN1, and ypN2-3. The role of PMRT was separately evaluated in each group. Locoregional control, disease-free survival, and overall survival (OS) were estimated using the Kaplan-Meier method. The effect of PMRT was assessed by propensity score-matched analyses and multivariate Cox analyses.

Results: With a median follow-up of 72.9 months, 5-year locoregional control, disease-free survival, and OS rates were 86.3%, 68.4%, and 83.1% for the entire cohort, respectively. There were 490 (27.0%), 567 (31.3%), and 756 (41.7%) patients in the ypN0, ypN1, and ypN2-3 groups, respectively. PMRT significantly improved 5-year OS in the ypN2-3 group (74.2% vs 55.9%; P < .001) but had no effect on 5-year OS in the ypN0 group (93.1% vs 95.5%; P = .517) and ypN1 group (88.4% vs 87.8%; P = .549).

Conclusions: With modern systemic therapy, PMRT significantly improved OS in the ypN2-3 group but not in the ypN0 and ypN1 groups. Whether PMRT can be safely omitted in the ypN0 and ypN1 groups should be addressed prospectively.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Breast Neoplasms / mortality
  • Breast Neoplasms / pathology
  • Breast Neoplasms / radiotherapy*
  • Breast Neoplasms / therapy
  • Chemotherapy, Adjuvant / methods
  • Disease-Free Survival
  • Female
  • Humans
  • Kaplan-Meier Estimate
  • Lymph Node Excision
  • Lymph Nodes / pathology
  • Lymphatic Metastasis / pathology
  • Mastectomy
  • Middle Aged
  • Neoadjuvant Therapy / methods
  • Neoplasm Staging
  • Propensity Score
  • Proportional Hazards Models
  • Retrospective Studies
  • Young Adult