Contrary to speculation, long-term use of tamoxifen(Drug information on tamoxifen) (Nolvadex) does not affect mood or sexual functioning, according to British researchers who studied the use of this antiestrogenic drug in women who are at high risk of developing breast cancer.
Published in a recent issue of the Journal of Clinical Oncology (19:1885-1892, 2001), the study was based on information from two ongoing British double-blind, randomized trials of tamoxifen vs placebo over 5 years in 488 women. As expected, the researchers found that tamoxifen users had significantly more hot flashes (42% vs 29%), night sweats (43% vs 29%), and cold sweats (10% vs 3%), 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 overall quality of life differences between the groups, and tamoxifen had no effect on overall sexual activity: 80% of tamoxifen users were sexually active, compared to 75% in the placebo group. Also, more placebo users than tamoxifen recipients reported mood swings over the 5-year study (26% vs 22%), but the researchers concluded that 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 antiestrogenic 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 that can have estrogenic effects on certain parts of the body such as the uterus (similar to hormone replacement therapy) as well as antiestrogenic effects on the heart and brain. "This explains why its overall effect on things like sexual activity may be more balanced than once thought," said Dr. Fallowfield.