ATLANTA —Transdermal testosterone was no better than placebo for improving libido in female cancer survivors after 4 weeks, according to results of a randomized, blinded, crossover study presented at the annual meeting of the American Society of Clinical Oncology.
In the 131 women who completed the study, both testosterone and placebo provided similar significant improvements in libido.
The North Central Cancer Treatment Group's N02C3 study randomized 150 women to 10 mg/day transdermal testosterone in Vanicream (Pharmaceutical Specialties, Inc.) or placebo (vehicle alone) for 4 weeks, followed by a crossover to the opposite treatment arm for 4 weeks.
All women were postmenopausal with no active disease, and all had reported decreased sexual desire. The investigators excluded women with comorbidities that might confound results. Women were an average of 52 years old; 31% were receiving aromatase inhibitors during the study, and 47% were receiving tamoxifen. Most women (72%) had at least one intact ovary, 80% had received prior chemotherapy, and only 7% had received pelvic radiotherapy.
Efficacy was measured using the Changes in Sexual Functioning Questionnaire (CSFQ) after each 4-week period. The average CSFQ score was 5.5 with testosterone and 4.4 with placebo after the first period and 8.8 and 8.1 after the second period.
“These results might seem very surprising, given the plethora of evidence that shows that transdermal testosterone is effective,” said study author Debra L. Barton, Ph.D., in her presentation. She suggested that the exclusion of women on supplemental estradiol in this trial and its relatively short duration might account for these differences. She also noted that previous studies had reported modest benefits with testosterone.
Low libido is a common issue in female cancer survivors. This clinical impression is validated by the speed with which the trial reached, and actually exceeded, its predicted accrual, according to Dr. Barton, of the Mayo Clinic College of Medicine, Rochester, Minn.
Testosterone treatment significantly increased the levels of free testosterone and bioavailable testosterone in the serum. A safety analysis of self-reported symptoms revealed no differences in side effects associated with virilization.