Adjuvant Ovarian Function Suppression Improves Breast Cancer Treatment Outcomes

In younger women with hormone receptor (HR)-positive breast cancer, ovarian function suppression (OFS) after surgery drives large improvements in breast cancer-free interval when combined with drug therapy, according to new research published in the Journal of Clinical Oncology (published online June 27, 2017; doi:10.1200/JCO.2016.72.0946).

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Multiple clinical trials—The Suppression of Ovarian Function Trial (SOFT) and Tamoxifen and Exemestane Trial (TEXT)—evaluated the quality of life, adherence, and efficacy of adjuvant endocrine therapies for breast cancer. Researchers led by Gini F Fleming, MD, University of Chicago (IL), summarized data from the two trials, alongside data from a cohort of older premenopausal women.

Researchers from SOFT randomly assigned premenopausal women with HER2-negative breast cancer (aged < 35 years) who underwent surgery with or without chemotherapy to receive exemestane plus OFS, tamoxifen plus OFS, or tamoxifen alone. Among the 240 patients in the trial, the reported 5-year breast cancer-free interval was 67.1% (95% CI, 54.6%-76.9%) with tamoxifen alone, 75.9% with tamoxifen plus OFS (95% CI, 64.0%-84.4%), and 83.2% with exemestane plus OFS (95% CI, 72.7%-90.0%).

Patients with HER2-negative breast cancer (aged < 35 years) enrolled in TEXT received OFS with or without concomitant chemotherapy and were randomly assigned to exemestane plus OFS or tamoxifen plus OFS. Among the 145 patients enrolled, the reported 5-year breast cancer-free interval for exemestane plus OFS was 81.6% (95% CI, 69.8%-89.2%) and for tamoxifen plus OFS was 72.9% (95% CI, 66.2%-87.7%).

Quality of life symptoms negatively impacted by OFS for patients younger than 35 years included vasomotor symptoms (greatest worsening from baseline to six months) and loss of sexual interest. Level of symptom burden was similar in older premenopausal women.

Researchers concluded that adjuvant OFS combined with either tamoxifen or exemestane results in significant improvements in breast cancer-free interval compared with tamoxifen alone in patients aged younger than 35 years with HR-positive breast cancer. Menopausal symptoms are a significant factor when choosing to undergo this treatment, researchers acknowledged, but symptoms are no worse than those seen in older premenopausal women.—Zachary Bessette