2783 - Predictors of Sexual Function Decline Following Combined External Beam Radiation and Brachytherapy for Prostate Cancer

Purpose/Objective(s):

Predicting which patients will develop erectile dysfunction after radiation remains a challenging and important goal. Our study aims to determine if pre-treatment factors can predict long term decline in erectile function after combination brachytherapy and external beam radiation treatment for localized prostate cancer.

Materials/Methods:

A retrospective study of a large single-institution database was performed. Medical records of 1917 consecutive patients who were treated between 2010-2015 with prostate I-125 seed implant followed by intensity-modulated radiation therapy (IMRT) were analyzed. We investigated whether the following pre-existing comorbidities or factors were predictive of erectile dysfunction: hypertension (HTN), diabetes (DM), smoking status, age, severity of pre-existing urinary symptoms, presence of prostate nodule, pre-procedure hormonal ablative therapy, urinary morbidity (25% change in International Prostate Symptom Score (IPSS)), race, pre-procedure PSA, Gleason Score, use of alpha-blockers, and Body Mass Index (BMI).

Decline in erectile function was defined as a drop in 2 or more points in Question 1 of the Sexual Health Inventory for Men (SHIM Confidence): “How do you rate your confidence that you could get and keep an erection?” at the 12-month follow-up visit. ANOVA testing, logistic odds ratios, and logistic regression models were used for statistical analysis.

Results:

549 patients had complete records for scores at 0,6, and 12 months, and had pretreatment SHIM scores of 3,4, or 5. Baseline SHIM confidence was 3 in 237 patients, 4 in 170 patients, and 5 in 142 patients. At 12-months, predictive factors were advanced age, higher pre-treatment SHIM score, use of pre-treatment use of hormonal therapy, and the development of urinary morbidity. Pre-existing HTN, DM, smoking, race, pre-treatment PSA, Gleason score, use of alpha-blockers, and BMI were not significant.

Conclusion:

Although current standards for use of combination radiation therapy for prostate cancer have evolved, our study offers valuable insights to predictive pre-treatment factors for patients who undergo this treatment. Interestingly, medical conditions including hypertension, diabetes, and smoking were not predictive of decline in erectile function at one year. Advanced age and use of hormone ablative therapy were predictive of developing decline in erectile function. Onset of urinary morbidity after treatment and high pre-treatment SHIM confidence were also significant predictive factors. These data will help guide clinicians who counsel patients considering treatment options for localized prostate cancer.