Tamoxifen or exemestane plus ovarian suppression improves 8-year survival outcomes among women with premenopausal women with breast cancer compared with tamoxifen alone, according to a study published in The New England Journal of Medicine.1

Evaluation of the Suppression of Ovarian Function Trial (SOFT; ClinicalTrials.gov Identifier: NCT00066690) and Tamoxifen and Exemestane Trial (TEXT; NCT00066703) previously demonstrated that after 5 years of treatment, exemestane plus ovarian suppression significantly reduced the rate of breast cancer recurrence compared with tamoxifen plus ovarian suppression, while the addition of ovarian suppression to tamoxifen did not improve rates of recurrence versus tamoxifen alone.

After a median follow-up of 8 years, updated results for the SOFT and TEXT trials revealed that the 8-year disease-free survival (DFS) rate was 78.9% and 83.2% among patients who received tamoxifen alone and tamoxifen plus ovarian suppression, respectively (hazard ratio [HR], 0.76; 95% CI, 0.62-0.93; P = .009), and 85.9% among those treated with exemestane plus ovarian suppression.

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The 8-year overall survival (OS) rate was 91.5% among the tamoxifen-only group versus 93.3% for patients in the tamoxifen plus ovarian suppression group (HR, 0.67; 95% CI, 0.48-0.92; P = .01); the 8-year OS rate for patients treated with exemestane plus ovarian suppression was 92.1%.

Among patients who received chemotherapy and remained premenopausal, 8-year OS rates were 85.1%, 89.4%, and 87.2% for patients who received tamoxifen alone, tamoxifen plus ovarian suppression, and exemestane plus ovarian suppression, respectively.

For patients with HER2-negative disease who underwent chemotherapy, the 8-year disease recurrence rate was significantly lower in the exemestane plus ovarian suppression group compared with tamoxifen plus ovarian suppression (by 7.0 percentage points in SOFT; by 5.0 percentage points in TEXT).

Grade 3 or worse adverse events were observed in 24.6%, 31.0%, and 32.3% of patients in the tamoxifen alone, tamoxifen plus ovarian suppression, and exemestane plus ovarian suppression groups, respectively.

The authors concluded that “adding ovarian suppression to tamoxifen resulted in significantly higher rates of disease-free survival among premenopausal women than the use of tamoxifen alone. Further improvement was seen with exemestane plus ovarian suppression.”


  1. Francis PA, Pagani O, Fleming GF, et al. Tailoring adjuvant endocrine therapy for premenopausal breast cancer. N Eng J Med. 2018;379;122-137. doi: 10.1056/NEJMoa1803164