Sequencing of tamoxifen and radiotherapy after breast-conserving surgery in early-stage breast cancer

Lori J. Pierce, Laura F. Hutchins, Stephanie R. Green, Danika L. Lew, Julie R. Gralow, Robert B. Livingston, C. Kent Osborne, Kathy S. Albain

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

Purpose: Tamoxifen (TAM) is thought to exert a cytostatic effect on hormone-sensitive breast cancer cells. Some preclinical studies show reduced radiosensitivity in irradiated malignant mammary epithelial cells when pretreated with TAM; other studies refute these results. Recent randomized clinical trials suggest an antagonistic effect of TAM on cytotoxic therapy, with improved disease-free survival (DFS) with sequential versus concurrent TAM. An exploratory analysis was undertaken to evaluate the optimal sequencing of TAM and radiotherapy (RT) after breast-conserving surgery. Patients and Methods: Southwest Oncology Group trial 8897 (Intergroup 0102) randomly assigned node-negative women with T1-3 breast cancers to cyclophosphamide, doxorubicin, fluorouracil (CAF); CAF → TAM; cyclophosphamide, methotrexate, fluorouracil (CMF); and CMF → TAM. For this analysis, data are reported only in the TAM groups. RT was allowed either before adjuvant therapy (sequential [SEQ] RT; 107 patients) or after chemotherapy but concurrent with TAM (concurrent [CONC] RT; 202 patients). Survival data were adjusted for receptor status, age, and tumor size. Results: With a median follow-up of 10.3 years, 10-year DFS values were 83% and 83% for CONC versus SEQ RT groups (log-rank P = .73; P = .76 adjusted for patient characteristics), and 10-year overall survivals were 88% and 90%, respectively (log-rank P = .59; adjusted P = .65). Patterns of failure showed no increase in in-breast recurrence rates between CONC RT and SEQ RT groups, with 10-year local recurrence rates of 7% for CONC RT and 5% for SEQ RT (hazard ratio, 0.73; 95% CI, 0.26 to 2.04; P = .54). Conclusion: The current analysis does not suggest an adverse effect on local or systemic control with CONC versus SEQ TAM and RT in node-negative breast cancer. A randomized trial is encouraged to validate these results.

Original languageEnglish (US)
Pages (from-to)24-29
Number of pages6
JournalJournal of Clinical Oncology
Volume23
Issue number1
DOIs
StatePublished - Jan 1 2005

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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