Case selection for high-energy transurethral microwave thermotherapy

Abstract

Transurethral microwave thermotherapy (TUMT) is a minimally invasive outpatient procedure for the treatment of benign prostatic hyperplasia (BPH). Different devices and operating software have been used in various clinical trials. The objective of this study was to identify the possible baseline parameters that could be used to identify the best responders to different microwave devices and treatment programs. Data on three different high-energy thermotherapy devices (Urowave, Prostalund, and Prostatron) were collected and analyzed. At 1 year of follow-up, 166 patients were available for the Prostatron system. In all, 52 had a ≥ 50% change in both symptom score and peak flow rate, whereas 114 patients were considered nonresponders. Responders were characterized at baseline by a lower peak flow rate (8.80 versus 10.48 ml/s, P ≤ 0.0001) and a larger degree of outlet obstruction as measured by the URA parameter (45.33 versus 36.70 cmH₂O, P ≤ 0.0300); a larger energy dose was delivered to this group during treatment (173.36 versus 156.40 kJ, P ≤ 0.0258). A total of 19 patients were available from the Prostalund cohort. No significant difference was found in the values recorded for baseline parameters between responders (5 patients) and nonresponders (14 patients). Stratification of 143 patients treated with the Urowave resulted in 29 responders ( ≥ 50% improvement in both Q_max and AUA score) at 6 months of follow-up, with a significant difference being found in the baseline value recorded for peak flow rate (7.0 versus 8.0 ml/s, P ≤ 0.026). At 12 months, however, this significance difference could no longer be found. In conclusion, baseline parameters with significant predictive value for a clinical response could be identified for the Prostatron device only. The results of this study further confirm the importance of an extensive laboratory and clinical research program for a fuller understanding of the clinical response obtained with a certain microwave device and a particular treatment software and for provision of the greatest possible advantage from these new alternative treatments. Further exploratory work is required for a better understanding of the role of other parameters such as prostate tissue architecture and vascularity, the microwave frequency, the applicator design, the intraprostatic temperature, and the treatment duration in the clinical response to microwave thermotherapy.