Evaluation of Intravesical Prostatic Protrusion as a Predictor of Dutasteride-Resistant Lower Urinary Tract Symptoms/Benign Prostatic Enlargement With a High Likelihood of Surgical Intervention

Abstract

To investigate factors predicting that combination therapy would be insufficient in terms of efficacy, necessitating conversion to surgical intervention, in patients with lower urinary tract symptoms and/or benign prostatic enlargement. In total, 218 patients given combination therapy for 6 months or more were enrolled in our study. Candidate factors for surgical intervention before dutasteride administration were statistically analyzed. We also examined the proportion of stromal components in resected specimens of the intravesical prostatic protrusion (IPP) portion using the point-counting technique according to IPP grades. Combination therapy was effective and was thus continued in 172 patients, whereas 46 required surgical intervention. The comparison between these two groups, by multivariate analysis, revealed significant differences in IPP and total International Prostate Symptom Score (IPSS). IPP (odds ratio 1.133, P <.001) was the strongest independent factor predicting conversion to surgical intervention. Receiver operating characteristic analysis identified the optimal cutoff value of IPP to be 8 mm (area under the curve: 0.9). This value yielded a sensitivity of 91% and a specificity of 72%. In addition, the mean proportion of stromal components in resected specimens of IPP according to IPP grades was grade I: 96.7%, grade II: 57.8%, and grade III: 21.4% (P <.001 for all), respectively. Our results suggest that in lower urinary tract symptoms and/or benign prostatic enlargement associated with severe IPP, combination therapy might have insufficient efficacy due to a low proportion of stromal components, necessitating conversion to surgical intervention.