The Pharmaceutical Journal
Vol 276 No 7404 p673
10 June 2006

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Trial suggests survival benefit with exemestane

Postmenopausal women with hormone-sensitive, early breast cancer do better if they are switched to exemestane after a few years' treatment with tamoxifen, according to data from the intergroup exemestane study.

The study began in 1998 and examined outcomes for 2,352 women randomly assigned to exemestane after two to three years of tamoxifen treatment and 2,372 women who continued with tamoxifen for a full five years. In the intention-to-treat population, the improvement in survival after 4.8 years of follow up (two years after treatment had ended) was not statistically significant.

However, women with hormone-sensitive tumours, or unknown receptor status, who were switched to exemestane were less likely to have died than women who continued with tamoxifen (9.1 per cent of exemestane-treated women died compared with 10.9 per cent of tamoxifen-treated women, P=0.05). There was also a reduction in risk of disease relapse or death.

Judith Bliss, head of clinical trials at the Institute of Cancer Research in Sutton, Surrey, said: “When we designed this trial, tamoxifen was the gold standard of care taken for five years — but we know that patients get the most benefit in the early years. Now we know that switching to exemestane after two or three years is safe and improves the cure rate in this group of patients.”

Women who took only tamoxifen were more likely to develop blood clots or gynaecological problems such as uterine cancer, polyps or vaginal bleeding, while women in the exemestane group had more fractures.

Professor Bliss added that there is now up to three years’ post-treatment follow-up data that suggest that the benefits of switching to exemestane are maintained.

The data were presented at the American Society of Clinical Oncology annual meeting in Atlanta, Georgia, earlier this week.