Tamoxifen use not associated with decreased sexual functioning or mood swings

Long-term use of tamoxifen does not affect mood or sexual functioning as has been speculated, according to British researchers who studied use of the anti-estrogen drug in women at high risk of developing breast cancer.

Culling information from two ongoing British double-blind, randomized trials of tamoxifen versus use of a placebo over five years in 488 women, the researchers found that, as expected, tamoxifen users had significantly more hot flashes (42 vs. 29 percent), night sweats (43 vs. 29 percent), and cold sweats (10 vs. 3 percent), compared to the control group. Tamoxifen blocks the brain’s use of estrogen, thus producing menopause-like symptoms.

But, beyond these menopausal symptoms, there were no significant quality-of-life differences between the groups, and no effect of tamoxifen on overall sexual activity (80 percent of tamoxifen users were sexually active compared to 75 percent in the placebo group), the researchers said. Also, more placebo users reported mood swings than tamoxifen patients over the five-year study (26 vs. 22 percent), but the researchers determined those mood changes were largely unrelated to the clinical trial.

"This is good news for women at high risk of breast cancer who are considering using tamoxifen," said Lesley Fallowfield, PhD, of the University of Sussex. "Much publicity has been generated by various groups who believe that the anti-estrogenic effects of tamoxifen can be damaging to a woman’s health. We certainly should never underestimate the effect of menopausal symptoms on a patient’s quality of life, but our results are encouraging."

Tamoxifen is a complex drug, which can have estrogenic effects on certain parts of the body such as the uterus (similar to hormone replacement therapy) as well as anti-estrogenic effects on the breast and brain. This explains why its overall effects on things like sexual activity may be more balanced than once thought she said.

"Tamoxifen for the Prevention of Breast Cancer: Psychosocial Impact on Women Participating in Two Randomized Controlled Trials;" Lesley Fallowfield, DPhil, et al.; Cancer Research Campaign Psychosocial Oncology Group, University of Sussex, Brighton, United Kingdom. Vol. 19, No. 7 (April 1), 2001: pp 1885-1892.