Practice-Changing Data Revealed for Premenopausal HR+ Breast Cancer

Findings presented at 50th Annual Meeting of ASCO show aromatase inhibitor effective for premenopausal women when combined with ovarian function suppression.

A joint analysis of two phase III trials involving a total of 4690 premenopausal women with hormone-receptor—positive (HR+) breast cancer demonstrated that adjuvant use of the aromatase inhibitor (AI), exemestane, reduced relative risk of developing subsequent invasive cancer by 28% compared with tamoxifen when both agents were combined with ovarian function suppression (OFS). The exemestane + OFS treatment arm also showed a relative reduction in risk of breast cancer recurrence of 34%.

“The trials demonstrate that an aromatase inhibitor, previously recommended only for postmenopausal women is also effective for premenopausal women when combined with ovarian function suppression,” said Olivia Pagani, MD, of the Institute of Oncology of Southern Switzerland, who presented the combined results on behalf of the International Breast Cancer Study Group (IBCSG), June 1, 2014 at the 50^th Annual Meeting of ASCO.

“As a physician who routinely recommends ovarian function suppression as adjuvant therapy for some young patients, these results will change my practice. I will combine ovarian function suppression with an aromatase inhibitor rather than with tamoxifen.”

“Tamoxifen, for at least 5 years, with the option of adding OFS has been the standard treatment,” Pagani said regarding premenopausal woman with HR+ breast cancer. Using adjuvant AIs for 5 years is a more effective treatment strategy than 5 years of tamoxifen in many postmenopausal women, according to Pagani; however, this AI treatment was not available to premenopausal women, because AIs require the low estrogen levels that occur after menopause, and these levels can only be achieved in young women with OFS.

TEXT (Tamoxifen and EXemstane Trial) and SOFT (Suppression of Ovarian Function Trial) were designed to determine whether or not adjuvant therapy with exemestane + OFS improved outcomes in premenopausal women compared with tamoxifen + OFS.

The TEXT trial randomized 2672 premenopausal women with HR+ breast cancer who were ≤12 weeks from surgery (with or without planned chemotherapy or OFS) to tamoxifen + OFS for 5 years or exemestane + OFS for 5 years. The SOFT trial randomized 3066 premenopausal women with HR+ breast cancer who were ≤12 weeks from surgery (with no chemotherapy or ≤8 months from chemotherapy) to 5 years of tamoxifen, tamoxifen plus OFS, or exemestane plus OFS.

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