Tamoxifen Does Not Affect Sexual Functioning or Mood Swings

Contrary to speculation, long-term use of tamoxifen(Nolvadex) does not affect mood or sexual functioning, according to British researchers who studied the use of thisantiestrogenic drug in women who are at high risk of developing breast cancer.

Menopausal Symptoms

Published in a recent issue of the Journal of Clinical Oncology(19:1885-1892, 2001), the study was based on information from two ongoingBritish double-blind, randomized trials of tamoxifen vs placebo over 5 years in488 women. As expected, the researchers found that tamoxifen users hadsignificantly more hot flashes (42% vs 29%), night sweats (43% vs 29%), and coldsweats (10% vs 3%), compared to the control group. Tamoxifen blocks the brain’suse of estrogen, thus producing menopause-like symptoms.

But, beyond these menopausal symptoms, there were no significantoverall quality of life differences between the groups, and tamoxifen had noeffect on overall sexual activity: 80% of tamoxifen users were sexually active,compared to 75% in the placebo group. Also, more placebo users than tamoxifenrecipients reported mood swings over the 5-year study (26% vs 22%), but theresearchers concluded that those mood changes were largely unrelated to theclinical trial.

Encouraging Results

"This is good news for women at high risk of breast cancerwho are considering using tamoxifen," said Lesley Fallowfield, PhD, of theUniversity of Sussex. "Much publicity has been generated by various groupswho believe that the antiestrogenic effects of tamoxifen can be damaging to awoman’s health. We certainly should never underestimate the effect ofmenopausal symptoms on a patient’s quality of life, but our results areencouraging."

Tamoxifen is a complex drug that can have estrogenic effects oncertain parts of the body such as the uterus (similar to hormone replacementtherapy) as well as antiestrogenic effects on the heart and brain. "Thisexplains why its overall effect on things like sexual activity may be morebalanced than once thought," said Dr. Fallowfield.