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Breast Cancer · Endocrine Therapy · Premenopausal

SOFT

In premenopausal hormone-receptor-positive breast cancer, does ovarian suppression added to tamoxifen or exemestane improve disease control?

PopulationPremenopausal women randomized in SOFT; treatment duration 5 years.InterventionTamoxifen + ovarian suppression, or exemestane + ovarian suppression.ComparatorTamoxifen alone.Primary clinical outcomeDisease-free survival.

Absolute Effect

At 8 years, DFS was 83.2% with tamoxifen + ovarian suppression vs 78.9% with tamoxifen alone: +4.3 points, NNT ≈ 24. Exemestane + ovarian suppression was 85.9%, +7.0 points versus tamoxifen alone, NNT ≈ 15.

Harm / burden

Grade ≥3 adverse events occurred in 24.6% with tamoxifen alone, 31.0% with tamoxifen + ovarian suppression and 32.3% with exemestane + ovarian suppression. For tamoxifen + ovarian suppression, the absolute increase was 6.4 points (NNH ≈16).

Clinical interpretation

SOFT demonstrates that ovarian suppression adds a measurable absolute disease-control benefit, with the largest benefit from exemestane + ovarian suppression in higher-risk patients, at the cost of greater treatment burden.

Source

Francis PA, et al. N Engl J Med. 2018;378:436–446.

Current-practice context · reviewed 14 October 2026

SOFT supports ovarian-function suppression added to endocrine therapy for premenopausal HR-positive breast cancer patients at sufficient recurrence risk, with exemestane plus ovarian suppression providing greater recurrence reduction than tamoxifen alone in higher-risk groups. Absolute benefit is smaller for low-risk patients; weigh menopausal symptoms, bone health, fertility, adherence and chemotherapy-induced ovarian suppression.

Current guideline guidance ↗