Ejaculatory Function Following Stereotactic Body Radiation Therapy for Prostate Cancer

Abstract

Ejaculatory dysfunction after prostate radiation therapy is an important quality of life issue with limited management options. Given the high biologically effective doses (BEDs) that are delivered with stereotactic body radiation therapy (SBRT), ejaculatory dysfunction may be more common and/or more severe than with alternative external beam approaches. The purpose of this study is to evaluate ejaculatory preservation following SBRT for prostate cancer.231 patients on a prospective quality of life study (IRB#: 2009-510) with baseline ejaculatory capacity treated with prostate SBRT at a single institution from 2013 to 2019 were included in this analysis. Ejaculatory function was assessed via the validated Ejaculation Scale (ES-8) from the Male Sexual Health Questionnaire (Rosen RC et al, 2004). ES-8 scores range from 3 - 40 with lower values representing increased interference or annoyance. The ES-8 includes questions about ejaculate volume, ejaculatory pain, and bother. Patients completed the questionnaire on the first day of treatment and at 1, 3, 6, 9, 12, 18, and 24 months post-SBRT. Elderly patients (Age > 70) and those who received hormonal therapy were excluded from this analysis. All patients were treated to 35-36.25 Gy in 5 fractions delivered with a frameless robotic radiosurgery system. Data analysis was performed using XLStat. Minimally important differences (MID) were calculated by obtaining half the standard deviation at time of start of treatment.Mean age at treatment was 64.2 years. Minimum follow-up was 24 months. Mean composite ES-8 scores showed a decline in the first month following treatment then stabilized: 30.3 (baseline); 26.7 (1 month); 27.6 (3 month); 26.9 (6 month); 26.0 (9 month); 25.4 (12 month); 25.0 (18 month) and 25.3 (24 month). The decline from baseline to one month was statistically significant (P < 0.0001). A clinically significant decrease (MID = 3.5) was achieved at 1 month (-3.6) and from 9 months (-4.3) through 24 months (-4.9). Ejaculate volume was statistically significantly reduced at all time points post-SBRT. Ejaculate volume reduction was clinically significant (MID = 0.57) from 6-24 months post SBRT. There was a clinically significant increase (MID = 0.53) in pain with ejaculation at 1-month (-0.67), 9-months (-0.63), and 12-months (-0.59). Prior to treatment, 7.6% of men reported that they were very to extremely bothered by their ejaculatory dysfunction. This was significantly increased to 14.5% at one-year (P = 0.01) and to 10.6% at 18-months (P = 0.048) post-SBRT.Men undergoing SBRT monotherapy for prostate cancer have a small decline in their overall ejaculatory function from baseline to one-month post-treatment, but stable function thereafter. Bother with ejaculation peaked at one year then slowly declined. Longer follow-up is required to confirm the durability of these findings.