Among premenopausal women with hormone-positive, early breast cancer who are considered to have a high risk of a cancer recurrence, the use of Aromasin® (exemestane) versus tamoxifen improves cancer-free survival at 5 years. These results were recently published in the Journal of Clinical Oncology.
The majority of breast cancers, referred to as hormone-positive breast cancers, are stimulated to grow from exposure to the female hormones estrogen and/or progesterone. An important component of treatment for hormone-positive breast cancer is endocrine therapy, in which exposure of the cancer cells to estrogen is drastically reduced.
There are several different endocrine agents approved for the treatment of hormone-positive breast cancer. In addition, treatment to suppress the ovaries from producing estrogen (ovarian function suppression, or OFS), is often included in the treatment regimen. Optimal treatment strategies for premenopausal breast cancer patients continue to be explored, particularly among subgroups of patients in an attempt to individualize therapeutic approaches.
Researchers recently conducted two clinical trials, referred to as the TEXT (Tamoxifen and Exemestane Trial) and SOFT (Suppression of Ovarian Function Trial) trials, to compare different endocrine treatments for premenopausal women with breast cancer. The trials included a total of 4,891 women with hormone-positive, human epidermal receptor 2 (HER 2)-negative, early breast cancer. Patients were treated with one of three endocrine treatment strategies: exemestane plus OFS; tamoxifen plus OFS; or tamoxifen only.
Results from the SOFT trial at 5 years of endocrine treatment were the following:
- Patients who remained premenopausal after chemotherapy, and who were at an intermediate to high risk of developing a recurrence based on clinical and pathologic features of their cancer, experienced a 10%-15% improvement in cancer-free survival at 5 years if treated with exemestane/OFS, versus tamoxifen/OFS or tamoxifen only.
- Improved cancer-free survival with tamoxifen/OFS compared to tamoxifen alone occurred only in the group of women who were at a high risk of developing a recurrence.
- Among patients who had a low risk of a recurrence and did not receive chemotherapy, cancer-free survival at 5 years was similar between all endocrine treatment groups.
Results from the TEXT trial at 5 years of endocrine treatment were the following:
- Patients treated with exemestane/OFS had a 5%-15% improvement in cancer-free survival at 5 years, compared to those treated with tamoxifen/OFS.
- Similar to results from the SOFT trial, patients who had a low risk of developing a cancer recurrence and did not receive chemotherapy, achieved similar rates of cancer-free survival at 5 years, regardless of the type of endocrine therapy they received.
The researchers concluded that premenopausal women with hormone-positive, HER2-negative, early breast cancer, appear to achieve improved cancer-free survival at 5 years when treated with exemestane/OFS, versus tamoxifen. However, women who were at a low risk of developing a recurrence achieved similar outcomes, regardless of the endocrine therapy used in these trials.
Premenopausal women with hormone-positive, HER2-negative breast cancer should speak with their healthcare provider regarding their individual risks and benefits of all treatment options available.
Reference: Regan M, Francis P, Pagani O, et al. Absolute benefit of adjuvant endocrine therapies for premenopausal women with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer: TEXT and SOFT trials. Journal of Clinical Oncology. Published online before print April 4, 2016, doi: 10.1200/JCO.2015.64.3171. Available at: http://jco.ascopubs.org/content/early/2016/03/31/JCO.2015.64.3171.abstract?cmpid=sk_jco_earlyrel_em_t_all_04-11-16_earlart. Accessed April 19, 2016.
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