Tamoxifen or Exemestane With Ovarian Function Suppression Prolongs Breast Cancer-free Interval

According to an analysis of 2 studies published in the Journal of Clinical Oncology, women younger than 35 years with hormone receptor (HR)-positive breast cancer may see benefit in breast cancer-free interval (BCFI) from tamoxifen or exemestane combined with adjuvant ovarian function suppression (OFS) vs tamoxifen alone.

The Suppression of Ovarian Function Trial (SOFT; ClinicalTrials.gov Identifier: NCT00066690) and Tamoxifen and Exemestane Trial (TEXT; ClinicalTrials.gov Identifier: NCT00066703) evaluated the quality of life, adherence, and efficacy of adjuvant endocrine therapies among 582 younger women with breast cancer.

SOFT randomly assigned premenopausal women after surgery with or without chemotherapy to receive exemestane plus OFS, tamoxifen plus OFS, or tamoxifen alone.

In a subset of 240 women with HER2-negative breast cancer who had chemotherapy, the 5-year BCFI was 83.2% (95% CI, 72.7%-90.0%) for exemestane plus OFS, 75.9% (95% CI, 64.0%-84.4%) for tamoxifen plus OFS, and 67.1% (95% CI, 54.6%-76.9%) for tamoxifen alone.

TEXT randomly assigned patients after surgery to tamoxifen plus OFS or exemestane plus OFS, with optional chemotherapy. For 145 HER2-negative patients in TEXT, the 5-year BCFI with tamoxifen plus OFS was 79.2% (95% CI, 66.2%-87.7%), and with exemestane plus OFS was 81.6% (95% CI, 69.8%-89.2%).

For women under 35 receiving OFS, the most commonly observed symptoms which affected the quality of life were vasomotor symptoms and loss of sexual interest and arousal.

Menopausal symptoms occurred, but were not worse than in older women who were premenopausal. Around 20% of patients discontinued endocrine therapy prematurely.

The authors concluded that women younger than 35 with HR-positive breast cancer can see significant improvements in BCFI when receiving tamoxifen and exemestane with OFS vs tamoxifen alone.

Reference

1. Saha P, Regan MM, Pagani O, et al. Treatment efficacy, adherence, and quality of life among women younger than 35 years in the international breast cancer study group TEXT and SOFT adjuvant endocrine therapy trials. J Clin Oncol. 2017 Jun 27. doi: 10.1200/JCO.2016.72.0946 [Epub ahead of print]