THE SOFT AND TEXT CLINICAL TRIALS

Preventing Breast Cancer From Coming Back

The SOFT and TEXT clinical trials produced practice changing results in the treatment of breast cancer in young women, who may have a poorer long-term prognosis.

The research showed that the aromatase inhibitor, exemestane, is more effective than tamoxifen in preventing breast cancer recurrence in young women who also receive ovarian function suppression.

Younger women with breast cancer may have a poorer long term prognosis because the hormone oestrogen, which is produced by the ovaries before menopause, can stimulate the growth of cancer cells in patients with hormone-responsive breast cancer. If normal ovarian activity is stopped (ovarian function suppression), the production and action of oestrogen is decreased and growth of hormone-responsive breast cancer can be suppressed.

SOFT and TEXT examined whether exemestane, previously recommended only for postmenopausal women, is also effective for premenopausal women when combined with ovarian function suppression. Both SOFT and TEXT randomly assigned premenopausal women with hormone-sensitive breast cancer to post-operative treatment with exemestane plus ovarian function suppression for five years, or to tamoxifen plus ovarian function suppression for five years. The two trials were designed to be complementary and just over half the patients also received chemotherapy as decided with their doctor.

The studies found that treatment with exemestane plus ovarian function suppression reduced the risk of developing any invasive cancer by 28% and reduced the risk of developing further breast cancer by 34%, compared to treatment with tamoxifen plus ovarian function suppression. The research found that at five years, 92.8% of women remained free from breast cancer after treatment with exemestane plus ovarian function suppression, compared to 88.8% after tamoxifen plus ovarian function suppression.

Worldwide, 2,672 women were enrolled in TEXT, including 249 women from Australia and New Zealand. Similarly, 3,066 women were enrolled in SOFT worldwide and of these, 240 women were from Australia and New Zealand. The trials were conducted in Australia and New Zealand by Breast Cancer Trials.

Associate Professor Prue Francis Chaired the International Steering Committee responsible for the SOFT and TEXT clinical trials and was the senior author of the publication of the results.