Cancer Research Lab

In patients with early breast cancer, switching to an aromatase inhibitor after 2 to 3 years of tamoxifen therapy provides better survival than simply continuing tamoxifen for a further 2 or 3 years, Italian researchers report.

Previous reports have shown that as an adjuvant treatment for early breast cancer, aromatase inhibitors reduce the risk of recurrence compared tamoxifen. However, it has been unclear whether this actually translates into improved survival.

Dr. Francesco Boccardo, from the University and National Cancer Research Institute in Genoa, and colleagues note that in 1992 they began switching breast cancer patients from tamoxifen to an aromatase inhibitor based on the belief that it would improves outcomes. The current research represents a pooled analysis of data from two early studies conducted by the group.

The pooled analysis included 828 postmenopausal women with early breast cancer who were treated with tamoxifen for 2 to 3 years. Following this period, 415 of the patients were randomized to continue tamoxifen for 2 to 3 more years, whereas 413 switched to either aminoglutethimide or anastrozole for the remaining years.

The researchers’ findings appear in the March 15th issue of Cancer, published online February 12th.

Switching to an aromatase inhibitors led to a 39% reduction in both all-cause and breast cancer-specific mortality (p < 0.05 for both). Moreover, no increase in breast cancer-unrelated mortality was noted after the switch.

The strongest independent predictor of mortality was patient age, followed by tumor size, allocated treatment, and nodal status, the investigators state.

“The present data and mortality benefits emerging from the most recent reports of the other switching trials, together with those from a recent metaanalysis of the 3 switching trials with anastrozole, reinforce the indication of early switching to an aromatase inhibitor in women presently receiving adjuvant treatment with tamoxifen,” the authors conclude.