Can histopathology predict treatment outcome following high‐energy transurethral microwave thermotherapy of the prostate? Results of a biopsy study

Abstract

BACKGROUND.Despite good results of high-energy transurethral microwave thermotherapy (TUMT) in the treatment of benign prostatic hyperplasia, it is still difficult to predict the response to treatment on an individual basis. Besides clinical baseline parameters, intrinsic histological parameters are suggested to play a role in the response variance after TUMT. In this study we analyzed histological parameters (vessel density and epithelium-stroma (E/S) ratio) in patients who were selected for high-energy TUMT and related these parameters to clinical outcome. METHODS. We treated 42 patients with high-energy TUMT, who prior to treatment agreed upon ultrasonographic investigation of the prostate in combination with biopsies of the peripheral and transitional zones of the prostate. For all separate biopsy locations, the histological stained prostate slides were morphometrically quantified with computer assistance and analyzed for E/S ratio and vessel density. Response to treatment was measured by using standardized response evaluation criteria and was correlated with histological outcome. RESULTS. The E/S ratio in the inner gland biopsies tended to be higher in the good response group compared to the very poor responders. Furthermore, a clear trend was seen towards a lower vessel density in good responders. Large prostates and prostates with a high E/S ratio responded well to the high-energy thermotherapy. CONCLUSIONS. Histopathological parameters of the prostate tend to be moderately predictive for clinical response in this research population. Poor responders appeared to have a somewhat higher vessel density in all prostate biopsy sides, and there was also a trend towards a lower E/S ratio in these patients.

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“…Factors such as prostatic vessel density and epithelial/stromal ratio seem to be related to the outcome, but the findings are difficult to translate into clinical use. D'Ancona et al [27] found large inter-individual variation, and thus it will be very difficult to establish thresholds of these variables to be used as predictors in each patient. Furthermore, there are no reliable noninvasive methods to measure these 'intrinsic' prostate characteristics, or they are not fully developed.…”

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“…In particular, the distribution of histologic components (epithelium/stromal ratio and blood-vessel density) has been proposed as determinative of the reaction of the prostate to the application of heat. 33 However, no significant difference could be detected for either the epithelial/stromal ratio or vessel density in good and poor responders.…”

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“…The wide range of outcomes in apparently similar patients led to research aiming to establish pretreatment factors that could be used to predict the results. Currently it is thought that small prostate volume, a low grade of obstruction, age, low epithelial/stromal ratio, low PSA level, low energy delivery and high prostate vascularity are independent predictors of a poor outcome [13–15].…”