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ACOG 2017: Prolonged Tamoxifen vs Oophorectomy in Estrogen Receptor–Positive Breast Cancer

By: Meg Barbor, MPH
Posted: Friday, June 2, 2017

Prolonged tamoxifen therapy is preferable to ovarian ablation followed by aromatase inhibitor therapy in premenopausal women with estrogen receptor–positive breast cancer who have been treated with tamoxifen for 5 years, according to the results of a modeling study presented by Janice S. Kwon, MD, of the University of British Columbia, Vancouver, and colleagues, at the 2017 American College of Obstetricians and Gynecologists (ACOG) Annual Meeting (Abstract 110P).

“Short-term evidence suggests that aromatase inhibitors have an advantage over tamoxifen,” stated Dr. Kwon in a recent interview. However, when a woman with estrogen receptor–positive breast cancer undergoes oophorectomy, she is at greater risk for such complications as bone loss and heart attacks due to the fact that she cannot proceed to hormone replacement therapy.

The investigators compared three treatment regimens: 5 additional years of tamoxifen, ovarian ablation followed by an aromatase inhibitor, and no additional treatment. A simulation of treatment-related adverse events predicted that 5 additional years of tamoxifen would lead to more cases of endometrial cancer and thromboembolic events, whereas ovarian ablation followed by an aromatase inhibitor may produce more bone fractures, coronary heart disease events, and strokes.