Venlafaxine, one of the newer antidepressant drugs, alleviates hot flashes in about 60 percent of breast cancer survivors and other women with postmenopausal symptoms, according to a new study conducted by the North Central Cancer Treatment Group, a clinical trials cooperative group based at Mayo Clinic.

The study will be published in the December 16 issue of The Lancet. This study was orally presented at the American Society of Clinical Oncology meeting in New Orleans, La., on May 21, 2000.

"The results seen with venlafaxine represent the most effective nonhormonal treatment reported to date for alleviation of hot flashes, which are a major clinical problem for many breast cancer patients and other postmenopausal women," says Charles Loprinzi, M.D., a Mayo Clinic medical oncologist and the principal investigator of the study. "Given that we studied three different doses, we also now know what dosage produces the optimal effect: an initial daily dose of 37.5 milligrams, to be increased to a maximum of 75 milligrams daily as needed."

Hot flashes can be a significant complaint for women experiencing diminished ovarian function as a result of menopause. Hot flashes may be particularly problematic for women who have had breast cancer. A commonly prescribed oral medication for breast cancer, tamoxifen, has been found to cause hot flashes. Hot flashes also may occur as a result of chemotherapy, which may induce a premature menopause.

In addition, many women suffering hot flashes reject estrogen therapy that might bring relief, due to concern that estrogen might promote breast cancer. A previous North Central Cancer Treatment Group study demonstrated that megesterol acetate is an effective nonestrogenic treatment for women with this concern, reducing hot flashes by 80 percent. Nonetheless, megestrol acetate is a female hormone derivative (progesterone), and some patients and physicians are reluctant to use any hormone product in women with a history of breast cancer.

Thus, the search for a viable nonhormonal method for alleviating hot flashes ensued, including previous North Central Cancer Treatment Group studies of vitamin E as well as clonidine, a blood pressure medication. Results from these studies, however, were less than satisfactory. "Nonhormonal means tested to date have limited efficacy and/or bothersome side effects which limit their utility," says Dr. Loprinzi.

Anecdotal reports of hot flash alleviation during venlafaxine treatment for depression prompted its consideration as a hot flash treatment. After a pilot study conducted at Mayo Clinic provided additional data suggesting this drug's effectiveness in remedying hot flashes, the North Central Cancer Treatment Group investigators undertook the current larger study.

This current placebo-controlled clinical trial evaluated three different doses of venlafaxine. The trial involved 229 patients, the majority of whom had a history of breast cancer. All of the women had bothersome hot flashes, with at least 14 hot flashes per week. Patients in the trial completed daily diary hot flash questionnaires for a baseline week and during the four-week treatment period. The dose of venlafaxine discovered to be optimal in this trial (37.5 mg/day for one week, then increasing this to 75 mg/day) reduced hot flashes by 61 percent, compared to a 27 percent reduction in hot flashes seen in patients receiving placebo.

This drug was well tolerated by most patients. Side effects at this dose, including mouth dryness, appetite suppression and nausea, were seen in a minority of patients. In most patients, the nausea was a temporary problem that generally resolved after a couple of weeks.

The study investigators also noted that patients' overall quality of life, measured by two quality-of-life questions before and after treatment, mildly increased at the end of the study for patients taking any dosage of venlafaxine compared to those taking placebo. In addition, the investigators found that venlafaxine doses of 37.5 to 150 milligrams per day did not seem to cause problems with libido when measured during the four weeks of therapy. Decreased libido recently has been reported as a side effect of some of the newer antidepressant drugs.