Results from two randomized clinical trials, published online ahead of print in Cancer, indicate that women taking tamoxifen after surgery for breast cancer who switch to an aromatase inhibitor after 2 or 3 years have improved survival compared with women who continue tamoxifen for an additional 2 or 3 years.

The investigators combined the results from the GROCTA 4B trial, which tested the aromatase inhibitor aminoglutethimide, and the ITA trial, which tested the aromatase inhibitor anastrozole (Arimidex). Combination of the data was planned into the design of the ITA trial, which was performed by the same collaborative group as GROCTA 4B.

In GROCTA 4B, investigators randomly assigned women who had already been taking tamoxifen for an average of 3 years to either continue taking tamoxifen at the same dose for an additional 2 years or to switch to aminoglutethimide for an equivalent period of time. The design of ITA mirrored that of GROCTA 4B, except that women assigned to switch drugs were given anastrozole.

In the combined analysis, all-cause mortality and breast cancer-related mortality were both significantly improved in women who switched to one of the aromatase inhibitors. Although the trials had several limitations, including the fact that neither trial reached its recruitment goal, the results mirror those of other recently published studies.