Safety and efficacy of topical testosterone in breast cancer patients receiving ovarian suppression and aromatase inhibitor therapy

Premenopausal, high-risk, hormone receptor-positive breast cancer patients are often treated with ovarian suppression in combination with aromatase inhibitors (AI). This combination has important adverse effects, particularly in sexual function, such as vaginal dryness and loss of libido. There is no effective therapy for reduced sexual function in this setting. Our study aimed to determine the efficacy and safety, particularly regarding sexual function, of a low-dose, topical testosterone gel administration. This is a pilot, single-center study, designed to evaluate the efficacy of topical testosterone gel (3 mg/day) in improving sexual function in 29 premenopausal patients on ovarian suppression in combination with an AI. The primary safety endpoint was to assess serum estradiol elevation. The primary efficacy endpoint was sexual function improvement, assessed by the Female Sexual Function Index questionnaire. We report the results on 29 patients. Twenty-two patients (75%) completed the 3-month treatment, and seven discontinued treatment before completion, mostly due to logistical difficulties related to the COVID-19 pandemic. All patients maintained the value of baseline mass spectrometry assay for estradiol of less than 2.7 pg/mL during the undertaken measurements. We observed a significant improvement in Female Sexual Function Index measures over the visits, with an increase from a mean of 11.7 at baseline to 19.1 in the third month (p < 0.001), with the greatest improvement observed between the second and third months. Our findings suggest that topical testosterone seems to be safe and may be effective in improving sexual function in patients on ovarian suppression and AI. The project was submitted and approved through the hospital’s SGPP platform in 11/26/2019 (Project No. SGPP 393819) and CAAE (Research Ethics Committee) (CAAE No 25609719.5.0000.007).