Urinary function after image-guided intensity modulated radiation therapy (IG-IMRT) of localized prostate cancer.

Abstract

141 Background: Men choosing treatment for prostate cancer risk potential urinary dysfunction or incontinence. The purpose of this study was to determine the effect of high dose image-guided intensity modulated radiation therapy (IG-IMRT) on urine control and function in such men. Methods: Between March 31, 2008 and September 28, 2012, 3,602 men received high dose IG-IMRT for localized prostate cancer with sufficient data for review, including baseline and minimum 11 month follow-up evaluation of urine control and function. The latter were determined by a urinary continence grading questionnaire and the International Prostate Symptom Score (IPSS). These questionnaires were completed by all men prior to radiation (baseline) and at every follow up visit. The continence questionnaire separated patients as G0: no incontinence, G1: minimal incontinence not requiring pads, G2: incontinence requiring pads, and G3: incontinence interfering with daily life activities. Men with IPSS scores of 0 to 7 were deemed mildly, 8 to 19 moderately, and 20 to 35 severely symptomatic. Typical therapy was 8100 cGy delivered to the prostate in 45 fractions. Pelvic lymph nodes were treated in 13% (458) of the cases. Results: At baseline, incontinence grading in our 3,602 men was G0 in 3,086 (86%), G1 in 479 (13%) and G2/3 in 37 (1%) and IPSS was 0-7 in 2092 (58%), 8 to 19 in 1,276 (35%) and 20 or more in 233 (6.5%). After IG-IMRT, 2,635 (85%) of baseline GO men remained continent, 408 (13%) developed G1 incontinence and 43 (1.1%) developed G2/3 incontinence. Of 479 baseline G1 incontinent men, 259 (54%) improved to G0. Of 37 baseline G2/G3 incontinent men, 21 (57%) improved to G0/1 incontinence. In 2,092 mildly symptomatic men by IPSS (average 3.5 at baseline), there was a rise to 5.4 but 1,619 (77%) remained mildly symptomatic. In the 1,276 moderately symptomatic men at baseline the average IPSS (12) decreased to 9.8 at last follow up (p<0.001). Similarly, in the 233 severely symptomatic men at baseline the average IPSS (24) dropped to 13 at last follow up (p<0.001). Conclusions: Urinary incontinence following high dose IG-IMRT for prostate cancer is rare. IG-IMRT seems to improve some men with baseline urinary incontinence and higher IPSS scores. High dose IG-IMRT remains a good treatment option for localized prostate cancer.