Endocrine Therapy on Trial in Male Breast Cancer
Posted: Thursday, November 29, 2018
Although not without controversy, the final results of what the authors call the “first prospective, randomized, multicenter trial evaluating the efficacy and safety of [three] different endocrine treatment options in male patients with breast cancer” were discussed at the 2018 European Society for Medical Oncology (ESMO) Congress in Munich (Abstract 273PD_PR). According to an ESMO press release, the takeaway is that drugs used in the treatment of breast cancer in women may be effective and well tolerated in men.
Lead author Mattea Reinisch, MD, of Klinikum Essen-Mitte, Essen, Germany, and colleagues noted that tamoxifen is the standard of care in treating men with breast cancer, more than 90% of whom have hormone receptor–positive disease. Over 5 years, they randomly assigned 55 men about evenly to three 6-month treatment arms: (A) oral tamoxifen; (B) tamoxifen + subcutaneous gonadotrophin-releasing hormone analog (GnRHa); and (C) oral exemestane + GnRHa.
The median estradiol level in arm A increased by 67% after 3 months and by 41% after 6 months. In arms B and C, estradiol levels decreased 85% and 73%, respectively, after 3 months, and 59% and 63%, respectively, after 6 months. Notably, according to the ESMO news release, the results indicated that “tamoxifen had little impact on health-related quality of life or erectile function in [the] men…while the combination of GnRHa plus exemestane had a major adverse effect on both measures.”
“Tamoxifen monotherapy should be kept as standard hormonal therapy for men with breast cancer,” Dr. Reinisch said. “The [adverse] effects are moderate, hardly impairing sexual behavior.” The use of GnRHa agents in men with breast cancer is debated, the ESMO release noted, but can reduce testosterone when combined with such aromatase inhibitors as exemestane.
However, Agnes Jager, MD, PhD, of the Erasmus Medical University Cancer Institute in Rotterdam, the Netherlands, voiced concern over the study. “It is regrettable that…estradiol suppression at 3 months was the primary endpoint…,” she stated in an ESMO press release. “As far as I know, [this] is neither a validated nor a clinically useful surrogate endpoint for the efficacy of endocrine treatment.”