Predictors of treatment outcome for high-energy transurethral microwave thermotherapy

Transurethral microwave thermotherapy (TUMT) is an innovative alternative to transurethral resection of the prostate (TURP) for the treatment of lower urinary tract symptoms (LUTS) suggestive of bladder outflow obstruction (BOO). Although the results are satisfactory for the majority of the patients, a considerable number of patients have an unfavorable outcome. Thus, the identification of features able to predict efficacy of TUMT for individual candidates is an important issue.

The available literature in MEDLINE covering the predictive role of various baseline measures for the outcome of high-energy TUMT was reviewed. Direct comparison among various studies was not possible because of differences in thermotherapy devices, treatment protocols, and the definition of a good response to treatment.

Predictive features have been detected only for the Prostatron device. A small prostate volume, a low grade of BOO, and advanced age were independent predictors of poor outcome. The strongest predictive feature was the amount of energy delivered during treatment. Histologic characteristics (epithelial:stromal ratio and microvessel density) have not proved predictive for therapeutic outcome. The role of intraprostatic vascularization, as a regulator of the temperature during treatment, seems to be of the greatest importance, but results have not been presented yet.

The value of baseline clinical measures for the selection of the best candidates for TUMT is limited at best. Variations in the internal structure of the individual prostate seem to play the most important role in regulating the amount of energy absorbed during treatment, and further research must focus on this item.