(HealthDay News) — The American Society of Clinical Oncology (ASCO) is updating its guidelines on adjuvant endocrine therapy to recommend tamoxifen for up to 10 years for women with nonmetastatic hormone receptor-positive breast cancer. This updated clinical practice guideline was published online May 26 in the Journal of Clinical Oncology.

Harold J. Burstein, MD, PhD, from the Dana-Farber Cancer Institute in Boston, and colleagues from ASCO’s Update Committee conducted a literature review of randomized trials to evaluate the optimal duration of treatment for endocrine therapy, particularly adjuvant tamoxifen.

RELATED: Breast Cancer Resource Center

Continue Reading

The authors identified five studies of tamoxifen therapy that extended treatment beyond five years. There was a breast cancer survival advantage with 10-year durations of tamoxifen use in the two largest studies with the longest reported follow-up. For 10 years of tamoxifen therapy, compared with five years, lower risks of breast cancer recurrence and contralateral breast cancer were seen.

“If women are pre- or perimenopausal and have received five years of adjuvant tamoxifen, they should be offered 10 years total duration of tamoxifen,” the researchers wrote. 

“If women are postmenopausal and have received five years of adjuvant tamoxifen, they should be offered the choice of continuing tamoxifen or switching to an aromatase inhibitor for 10 years total adjuvant endocrine therapy.”

Several authors disclosed financial ties to the pharmaceutical industry.


  1. Burstein HJ, Temin S, Anderson H et al. Adjuvant Endocrine Therapy for Women With Hormone Receptor–Positive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline Focused Update. J Clin Oncol. 2014;doi:10.1200/JCO.2013.54.2258.