Impact of SERM adherence on treatment effect: International Breast Cancer Study Group Trials 13-93 and 14-93

Olivia Pagani, Shari Gelber, Marco Colleoni, Karen N. Price, Edda Simoncini

Research output: Contribution to journalArticle


The degree of adherence to oral anticancer agents may influence treatment efficacy. Tamoxifen and toremifene usage data from two International Breast Cancer Study Group (IBCSG) studies were used to evaluate the impact of treatment adherence on the efficacy of these two selective estrogen receptor modulators (SERMs). Between 1993 and 1999, IBCSG Trial 13-93 randomized premenopausal women with node-positive disease to tamoxifen or no endocrine therapy and IBCSG Trial 14-93 compared tamoxifen and toremifene in postmenopausal women with node-positive disease. 690 women with estrogen-receptor positive enrolled in these two trials were alive and disease-free 4 years after the start of SERM. The median follow up for this analysis was 9.0 years. Using a Kaplan-Meier landmark analysis at 4 years, the 609 women completing at least 4 years of SERM had improved 10-year disease-free survival (DFS) (71 %) compared with the 81 women taking less than 4 years (64 %), but these differences did not reach statistical significance [DFS hazard ratio (

Original languageEnglish
Pages (from-to)455-459
Number of pages5
JournalBreast Cancer Research and Treatment
Issue number2
Publication statusPublished - Nov 2013



  • Breast cancer
  • Endocrine treatment
  • Selective estrogen receptor modulators
  • Tamoxifen
  • Toremifene
  • Treatment adherence

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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