According to the results of an international study, postmenopausal women who have taken tamoxifen for early stage estrogen-receptor positive breast cancer for two to three years might increase their chances of survival by switching to newer breast cancer drugs called aromatase inhibitors.

Study researchers found this drug switch-up reduced the number of events linked to poor survival by 32 percent -- although no difference has been found in overall survival at this early point in the trial.

"These findings provide some limited evidence to advise all women being administered tamoxifen to switch, even though this approach is not devoid of potentially serious side effects," say experts at the National Cancer Institute.

Side effects appear to be minimal, however, and the up side of treatment with aromatase inhibitors is the fact that they don't seem to carry the risk of death from other causes like with tamoxifen, which can cause stroke or endometrial cancer.

This study is expected to be published in the March 15 issue of the journal Cancer.