Long-term survival outcomes following internal mammary node irradiation in stage II-III breast cancer: results of a large retrospective study with 12-year follow-up

Int J Radiat Oncol Biol Phys. 2013 Aug 1;86(5):867-72. doi: 10.1016/j.ijrobp.2013.02.037. Epub 2013 Jun 6.

Abstract

Purpose: To examine the effect of internal mammary node irradiation (IMNI) on disease-free survival (DFS) and overall survival (OS) in breast cancer patients treated with modified radical mastectomy and postoperative radiation therapy.

Methods and materials: Between 1994 and 2002, 396 patients with stage II-III breast cancer were treated with postmastectomy radiation therapy with (n=197) or without (n=199) IMNI. Patients who received neoadjuvant chemotherapy were excluded. IMNI was administered at the clinical discretion of the treating physician. Median RT dose was 50.4 Gy (range, 45.0-59.4 Gy) in 28 fractions, with inclusion of the supraclavicular fossa in 96% of patients. Adjuvant chemotherapy was administered to 99.7% of the patients and endocrine therapy to 53%.

Results: The median follow-up was 149 months (range, 124-202). IMNI patients had more advanced nodal stage and non-high grade tumors than those without IMNI (P<.001). Otherwise, disease and treatment characteristics were well balanced. The 10-year DFS with and without IMNI was 65% and 57%, respectively (P=.05). Multivariate analysis demonstrated that IMNI was an independent, positive predictor of DFS (hazard ratio [HR], 0.70; P=.02). Benefits of IMNI in DFS were seen most apparently in N2 patients (HR, 0.44; 95% confidence interval [CI], 0.26-0.74) and inner/central tumors (HR, 0.55; 95% CI, 0.34-0.90). The 10-year OS with and without IMNI was 72% and 66%, respectively (P=.62). The 10-year DFS and OS were 61%, and 69%, respectively.

Conclusions: Internal mammary node irradiation significantly improved DFS in postmastectomy breast cancer patients. Pending long-term results from randomized trials, treatment of internal mammary nodes should be considered in postmastectomy radiation therapy.

Publication types

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

MeSH terms

  • Adult
  • Aged
  • Analysis of Variance
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Axilla
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / mortality*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / radiotherapy*
  • Breast Neoplasms / surgery
  • Carcinoma, Ductal, Breast / drug therapy
  • Carcinoma, Ductal, Breast / mortality
  • Carcinoma, Ductal, Breast / pathology
  • Carcinoma, Ductal, Breast / radiotherapy
  • Carcinoma, Ductal, Breast / surgery
  • Carcinoma, Lobular / drug therapy
  • Carcinoma, Lobular / mortality
  • Carcinoma, Lobular / pathology
  • Carcinoma, Lobular / radiotherapy
  • Carcinoma, Lobular / surgery
  • Chemotherapy, Adjuvant / methods
  • Disease-Free Survival
  • Female
  • Follow-Up Studies
  • Humans
  • Lymph Node Excision / methods
  • Lymphatic Irradiation / mortality*
  • Mastectomy, Modified Radical / methods
  • Mastectomy, Modified Radical / mortality
  • Middle Aged
  • Neoplasm Recurrence, Local / mortality
  • Neoplasm Recurrence, Local / pathology
  • Retrospective Studies
  • Young Adult