TUESDAY, Sept. 2 (HealthDay News) -- Contrary to previous study results, the cancer prevention drug anastrozole does not appear to cause impairment of cognitive performance, a new study found.

Anastrozole has been shown to be superior to tamoxifen in preventing breast cancer recurrence in postmenopausal women. But some "cross-sectional" studies have suggested that endocrine therapies such as anastrozole are associated with poorer performance on verbal memory and processing tasks.

For the new study, published in the October edition of The Lancet Oncology, researchers randomly assigned postmenopausal women to receive anastrozole or a placebo daily for five years.

Before the study began, and for six months and 24 months after starting treatment, a subset of 227 of the women underwent tests to measure their cognitive performance, including auditory verbal tasks, logical memory tasks, spatial span tests, and verbal fluency assessments.

There was no difference between the anastrozole or placebo groups at six months or 24 months in changes in attention or memory, or in the number of women who experienced cognitive decline in three or more cognitive tasks.

The only difference between the groups was that at the 24-month time point, significantly more women in the anastrozole group reported experiencing hot flushes.

The authors of the study pointed out that more research is needed to determine the longer-term effects of anastrozole, but said their findings were good news for women who take the medication.

"These findings should be reassuring in the short term for postmenopausal women being treated with anastrozole, their clinicians and carers," they wrote.

This study was part of the International Breast Intervention Study.

More information

The U.S. National Cancer Institute has more about anastrozole.