Mayo Clinic researchers working with other North Central Cancer Treatment Group (NCCTG) investigators have found that a single dose of depomedroxyprogesterone acetate (MPA) more effectively reduces hot flashes than does the antidepressant venlafaxine (Effexor®). Results of the study are available online in the Journal of Clinical Oncology.

Hot flashes are a major problem for many women as they approach menopause. Estrogen-based therapy had been the standard for many years, resulting in an 80 to 90 percent reduction in hot flashes. However, concerns about a link between estrogen and progesterone combined therapy and an increased risk of breast cancer, heart disease and/or cognitive dysfunction were reported in articles about the “Women’s Health Initiative” published in JAMA in 2002 and 2004, and have led to a search for alternate therapies.

Some newer antidepressants such as venlafaxine (Effexor®) and some progestin-based drugs such as megestrol acetate (Megace®) or MPA (Depo-Provera™) are non-estrogen ways of treating hot flashes.

No reports were published previously comparing the efficacy of the newer antidepressants to hormone therapy for treating hot flashes. Charles Loprinzi, M.D., Mayo Clinic oncologist and lead author of the study, and his fellow researchers conducted this study to make that comparison, hoping to identify the best available alternative.

Patients were randomly selected to receive either 75 milligrams of venlafaxine orally every day or one 400 milligram intramuscular shot of MPA, and then report on hot flashes, potential side effects and quality of life issues over a six-week period. The reduction in hot flashes was significantly greater in the group receiving MPA than the group receiving venlafaxine (79 percent versus 55 percent reduction). The effectiveness of the single dose of MPA was similar for cancer patients with or without tamoxifen therapy, and treatment effectiveness also appeared be the same for women with or without a history of breast cancer.

Although follow-up information is not available for all the patients after six weeks, the collected data indicated that the improved hot flash benefit appeared to last for at least six months in some women following the single MPA dose. Almost three times as many MPA patients still reported a 90 percent reduction in hot flashes after six months, compared to those receiving venlafaxine.

While both venlafaxine and MPA appear to be well tolerated, MPA shows a distinct advantage in the early part of treatment, with the patients receiving venlafaxine reporting more nausea, appetite loss, dizziness, constipation, mouth dryness and sleepiness. One shot of MPA also costs significantly less than a three-month supply of venlafaxine. The obvious benefits need to be weighed against the uncertainty that exists with regard to MPA safety, in terms of risk for breast cancer, says Dr. Loprinzi. “While there is some data to suggest that MPA might slightly increase breast cancer risk, other data suggest that MPA, when not given in combination with estrogen, might decrease risk,” he says. “Given that, MPA does provide a treatment option that is reasonable for women to consider.”

Other Mayo Clinic researchers involved with this study include Debra Barton, Ph.D., and Jeff Sloan, Ph.D. Additional NCCTG investigators include: Ralph Levitt, M.D., Meritcare Hospital Community Clinical Oncology Program (CCOP), Fargo, N.D.; Shaker Dakhil, M.D., Wichita CCOP, Wichita, Kan.; Daniel Nikcevich, M.D., Duluth CCOP, Duluth, Minn.; James Bearden III, M.D., Upstate Carolina CCOP, Spartanburg, S.C.; James Mailliard, M.D., Missouri Valley Cancer Consortium, Omaha, Neb.; Loren Tschetter, M.D., Sioux Community Cancer Consortium, Sioux Falls, S.D.; Tom Fitch, M.D., Scottsdale CCOP, Scottsdale, Ariz.; and John Kugler, M.D., Illinois Oncology Research Association CCOP, Peoria, Ill.