TUESDAY, Feb. 13 (HealthDay News) -- Switching to newer breast cancer drugs, called aromatase inhibitors, after two to three years of treatment with tamoxifen may extend disease-free survival and slightly reduce the risk of death in women who've been treated for early stage disease, an international study finds.

The Intergroup Exemestane Study (IES) tracked more than 10,000 breast cancer patients for a median follow-up of almost five years. The researchers looked at the impact of changing from tamoxifen to the aromatase inhibitor exemestane (brand name, Aromasin).

The researchers found that switching to exemestane reduced the number of events linked to poorer survival by 32 percent.

"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," Francesco Boccardo and Alessandra Rubagotti, of the National Cancer Institute and University of Genoa Medical School in Italy, wrote in an accompanying comment to the study.

However, the two experts noted that the incidence of serious side effects "was low, and the available data do not indicate any increase in the risk of death unrelated to breast cancer in the women switched to aromatase inhibitors."

Boccardo is lead author of another new study, released Monday, that found that switching from tamoxifen to an aromatase inhibitor could significantly extend survival in postmenopausal breast cancer patients. That study is expected to be published in the March 15 issue of the journal Cancer.

Tamoxifen has been associated with increased risk of death from other causes, such as stroke or endometrial cancer. By using aromatase inhibitors instead of tamoxifen, breast cancer patients may avoid such risks, Boccardo and his colleagues said.

More information

The U.S. National Cancer Institute has more about aromatase inhibitors.