(HealthDay)—The addition of ovarian suppression to tamoxifen is associated with increased survival versus tamoxifen alone among premenopausal women with breast cancer, according to a study published online June 4 in the New England Journal of Medicine to coincide with the annual meeting of the American Society of Clinical Oncology, held from June 1 to 5 in Chicago.

Prudence A. Francis, M.D., from the University of Melbourne in Australia, and colleagues randomized premenopausal women to five years of tamoxifen, tamoxifen plus ovarian suppression, or exemestane plus ovarian suppression in the Suppression of Ovarian Function Trial (SOFT) and to tamoxifen plus ovarian suppression or exemestane plus ovarian suppression in the Tamoxifen and Exemestane Trial (TEXT).

The researchers found that the eight-year disease-free survival rate was 78.9, 83.2, and 85.9 percent for tamoxifen alone, tamoxifen plus ovarian suppression, and exemestane plus ovarian suppression, respectively, in SOFT. The corresponding eight-year overall survival rates were 91.5, 93.3, and 92.1 percent. The eight-year distant recurrence rate was lower with exemestane plus ovarian suppression versus tamoxifen plus ovarian suppression in women with human epidermal growth factor receptor 2-negative cancers who underwent chemotherapy (by 7 and 5 percentage points in SOFT and TEXT, respectively).

"The addition of ovarian suppression to tamoxifen resulted in significantly higher eight-year rates of both disease-free and overall survival than tamoxifen alone," the authors write. "The use of exemestane plus ovarian suppression resulted in even higher rates of freedom from recurrence."

Several authors disclosed ties to pharmaceutical companies, including Pfizer and Ipsen. The study was partially funded by Pfizer; Pfizer and Ipsen provided the trial drugs.

More information: Abstract/Full Text
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Journal information: New England Journal of Medicine