SOFT Trial Results Inconclusive: Further Study Needed

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Edith A. Perez, MD

The challenge here is that the decision for chemotherapy was left to physician discretion, so the study does not provide guidelines on how to exactly assign need for chemotherapy.

—Edith A. Perez, MD

The results of the SOFT trial—presented at the 2014 San Antonio Breast Cancer Symposium, reported recently by Francis et al in The New England Journal of Medicine,1 and reviewed in this issue of The ASCO Post—were not as conclusive as we had hoped. In essence, the study enrolled women with resected early-stage hormone receptor–positive breast cancer who were randomized to receive one of three antiestrogen approaches. The results demonstrated that most of these patients had a very good outcome in response to the physician’s decisions (in consultation with the patient) of surgery, chemotherapy, radiation therapy, plus one of the three hormonal approaches tested.

This is good news, although it does not imply that all women may not have had side effects of these treatments nor did not develop tumor recurrence or will not develop tumor recurrence in the years to come. However, at least at the reported follow-up, survival was greater than 95%, and about 85% of patients were alive without tumor ­recurrence.

Deciding Who Needs Chemotherapy

In terms of the main hypothesis of the trial, the results demonstrated that we cannot recommend ovarian function suppression as standard therapy for all patients with hormone receptor–positive breast cancer diagnosed in the premenopausal stage. This statement is based on the lack of statistical difference between tamoxifen and tamoxifen with ovarian function suppression. However, the important caveat to this overall “negative result” of this study is that for the subset of patients whose physicians thought they should receive chemotherapy, ovarian function suppression appeared to add to tamoxifen (or exemestane).

The challenge here is that the decision for chemotherapy was left to physician discretion, so the study does not provide guidelines on how to ­“exactly” assign need for chemotherapy. Therefore, we need to await further understanding of molecular profiling added to clinicopathologic characteristics to eventually make more informed and accurate decisions than those we can make today regarding who “needs” chemotherapy to optimize disease-free and overall survival.

Thus, we are still left with a situation where we need to continue discussing options with each patient, sharing the results of this trial (efficacy as well as toxicities observed), while awaiting further study follow-up related to long-term breast-related events to determine whether there are clinically relevant negative effects of ovarian function suppression. ■

Disclosure: Dr. Perez reported no potential conflicts of interest.


1. Francis PA, Regan MM, Fleming GF, et al: Adjuvant ovarian suppression in premenopausal breast cancer. N Engl J Med 372:436-446, 2015.


Dr. Perez is Deputy Director at Large, Mayo Clinic Cancer Center; Group Vice Chair, Alliance for Clinical Trials in Oncology; and Director, Mayo Clinic Breast Cancer Translational Genomics Program.



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