Episode 6: The SOFT trial: 12-Year Outcomes for Adjuvant Endocrine Therapy in Premenopausal Breast Cancer Patients
The SOFT trial investigates the impact of adding ovarian function suppression (OFS) to endocrine treatment with either tamoxifen or exemestane in premenopausal women with hormone receptor-positive breast cancer. Approximately 3,000 patients were assigned to one of three treatment groups: tamoxifen alone, tamoxifen plus OFS, or exemestane plus OFS. The primary endpoint was Disease-Free Survival (DFS), with secondary endpoints including Overall Survival (OS). After eight years of follow-up, the results demonstrated improved DFS and OS for patients receiving combined treatment with OFS and either tamoxifen or exemestane.
Now, the results after 12 years of treatment have been published. DFS and OS significantly improved for the groups receiving OFS with tamoxifen or OFS with exemestane compared to treatment with tamoxifen alone. Notably, there is a clear magnitude of benefit on OS, with a 2.2% improvement for OFS with tamoxifen and a 5.6% improvement for OFS with exemestane. Consequently, most premenopausal women are recommended to undergo treatment with OFS in combination with tamoxifen or an aromatase inhibitor like exemestane. The decision for OFS depends on the risk of relapse and the patient’s age. Specific subgroups, such as women under 35 years old, experienced meaningful improvements in 12-year OS when assigned to adjuvant OFS.
It was highlighted that in clinical practice, the results of OFS and exemestane are extrapolated to other aromatase inhibitors in cases of intolerance to exemestane. According to experts, OFS treatment ideally commences two weeks before adding the aromatase inhibitor. In very young patients, estradiol levels must be measured every three months for at least one year as a follow-up to ensure no endocrine activity.
In conclusion, after 12 years, there remains a clear benefit from incorporating OFS into endocrine treatment for premenopausal women with breast cancer. The absolute improvement in OS is even more pronounced in patients with a higher baseline risk of recurrence.
Ref: Prudence A. et al. (2022). Adjuvant Endocrine Therapy in Premenopausal Breast Cancer: 12-Year Results From SOFT. J Cli. Onc. 41: 1370-1375