3303 - Clinical Predictors of Long-Term Urinary Morbidity Following Combination Radiation Therapy for Prostate Cancer

Purpose/Objective(s):

Late genitourinary toxicity remains a clinically relevant concern following combination brachytherapy and external beam radiation (EBRT) for localized prostate cancer. Identifying pre-treatment predictors of urinary morbidity may improve patient selection and counseling. Our study aims to determine if pre-treatment factors can predict urinary morbidity at 12 months after combination radiotherapy for 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 urinary morbidity: hypertension (HTN), diabetes (DM), smoking status, age, severity of pre-existing urinary symptoms, presence of prostate nodule, pre-procedure hormonal ablative therapy, confidence in erectile function, race, pre-procedure PSA, Gleason Score, use of alpha-blockers, and Body Mass Index (BMI). Urinary morbidity was defined as a 25% increase from baseline in the International Prostate Symptom Score (IPSS) at the 12-month follow-up visit. ANOVA testing, logistic odds ratios, and logistic regression models were used for statistical analysis.

Results:

Of the records studied, 1152 patients had complete records for IPSS scores at 0,6, and 12 months. Gleason score was 7 or higher in 787 of 1152 patients (68%). Baseline IPSS was mild in 644 patients, moderate in 450 patients, and severe in 58 patients. Multivariable analysis of data at 12-months showed predictive factors were age, lack of pre-existing urinary morbidity, lack of pre-treatment use of alpha-blocker medications, prior hormonal therapy, confidence on SHIM questionnaire, and BMI. Pre-existing hypertension, diabetes, smoking, race, pre-treatment PSA, and Gleason score 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 those patients who undergo this treatment. Interestingly, medical conditions including hypertension, diabetes, and smoking were not predictive of urinary morbidity at one year. Generally, factors that were associated with young age and lack of urinary bother were associated with worsening voiding symptoms, while those with severe baseline urinary symptoms actually improved.