Bothersome Gynecomastia Following Neoadjuvant GnRH Agonists and Stereotactic Body Radiotherapy for Localized Prostate Cancer

Androgen deprivation therapy (ADT) is increasingly utilized in combination with stereotactic body radiotherapy (SBRT) for unfavorable prostate cancer. ADT such as gonadotropin releasing hormone (GnRH) agonists are known to cause hormonal-related side effects such as gynecomastia. The incidence of bothersome breast tenderness and/or enlargement following short course GnRH agonists and SBRT is unknown. This study sought to evaluate the timeline of gynecomastia as well as its relationship with testosterone recovery.Gynecomastia was self-reported via question 13b of a healthcare software prior to ADT initiation, the first day of robotic SBRT, and at each follow-up (1, 3, 6, 9, 12, 18, 24 and 36 months). The responses were grouped into three relevant categories (no problem, very small-small problem, and moderate-big problem). Scores were transformed to a 0-100 scale with higher scores reflecting less bother. Testosterone levels were measured at each follow-up.From 2007 to 2010, 122 localized prostate cancer patients (9 low-, 64 intermediate-, and 49 high-risk according to the D'Amico classification) at a median age of 72 years (range 54.5-88.3) were treated with short course ADT (3-6 months) and SBRT (35-36.25 Gy) at Georgetown University Hospital. Of the participants, 48% percent were non-white and 48% were overweight. 77% of patients received three months of ADT. At baseline, 2% of men experienced gynecomastia that was a "moderate to big problem" and that proportion peaked at 3 and 12 months post-SBRT (7%) before returning to less than baseline (0%) 24 months post-SBRT with a cumulative incidence of 14.75%. The median baseline healthcare software hot flash score of 98 declined to 90 at 3 months post-SBRT but this returned to baseline by 24 months post SBRT. These changes were both statistically and clinically significant (MID = 6.5). Testosterone recovery (> 230 ng/dL) occurred in approximately 70% of patients by 12 months post SBRT. The development and resolution of gynecomastia fluctuated at various timepoints and did not directly correlate with testosterone recovery.Bothersome gynecomastia occurs in less than 15% of men treated with neoadjuvant ADT. Resolution of gynecomastia occurs in most patients within two years after treatment. Reassurance of the temporary nature of gynecomastia may assist in reducing patient anxiety. Institutional IRB (IRB#: 2009-510) approval was obtained for retrospective review of prospectively collected data.