Tamoxifen is widely used to treat breast cancer. The drug is also being studied as a possible preventative treatment for women who are at high risk for the disease because of their family history, genetic markers, or other reasons. But because of tamoxifen’s complex interaction with estrogen-sensitive tissues in a woman’s body, some physicians worried that it might produce menopause-like symptoms, such as changes in mood or sexuality.

"There has been a great deal of adverse publicity centered around tamoxifen. Many women’s groups have rallied against it because of side effects. To hear these alarmist reports can be very distressing when you’re already anxious because of breast cancer or your risk of breast cancer," says lead author Lesley Fallowfield, PhD, a researcher with the Cancer Research Campaign (CRC) Psychosocial Oncology Group at the University of Sussex in Brighton.

The CRC researchers tracked 488 women who had a high family risk of breast cancer. Half of the women took tamoxifen to prevent breast cancer and half took a placebo, a pill that looked identical but contained no tamoxifen. The women reported on their mental condition, social activities, and sexual well-being every six months from 1992 to 1999.

The CRC group was interested in the psychosocial effects of tamoxifen because some groups have suggested that the drug may be dangerous when used for several years. A woman’s decision to use tamoxifen depends on how she views both the possible side effects of the drug and breast cancer itself, Fallowfield says. "Our results are encouraging in that general psychological and sexual functioning did not seem to be adversely affected by tamoxifen," she says.

The British study did find that women who took tamoxifen had dramatic shifts in mood, anxiety levels, and sexual functioning over time. But women who took the placebo had equally dramatic psychological swings. In both groups, mood swings were related to outside factors such as family relationships, general health, and satisfaction with work, not trial participation, say researchers. There was no difference at all in sexual activity or sexual functioning between the tamoxifen group and the placebo group.

"It’s reassuring that both groups of researches found the same thing, that there are no long term psychosocial effects from tamoxifen," said Heather Feigelson, PhD, senior epidemiologist for the American Cancer Society (ACS). "This should reassure patients and their physicians."

"There have been too many people ready to attribute all side effects and problems that a woman with breast cancer has to tamoxifen," says Fallowfield.

Breast cancer is the most common cancer in women after skin cancer, according to ACS statistics. About 192,200 women in the US will be diagnosed with invasive breast cancer this year. More than 75% of women who are diagnosed with breast cancer are age 50 or older. About 40,200 women will die from breast cancer in 2001.