Outcome predictors of high-energy transurethral microwave thermotherapy

Despite the good results of high-energy transurethral microwave thermotherapy (TUMT) for treatment of benign prostatic hyperplasia (BPH), it still is difficult to predict the response to treatment on an individual basis. In addition to clinical baseline parameters, histologic parameters seem to play a role in response variance after TUMT. High-energy TUMT has become widely accepted as a minimally invasive outpatient treatment in patients with lower urinary tract symptoms and BPH. Most patients benefit substantially from targeted microwave thermotherapy; however, little is known about optimal patient selection and the most relevant outcome parameters.

We evaluated Medline-based studies published between 1989 and 2000, including 900 patients suffering from lower urinary tract symptoms due to BPH who were undergoing TUMT. We evaluated outcome predictors for TUMT, such as histopathological parameters, prostate-specific antigen, and volume.

Histologic and clinical outcome parameters were identified. Patient-to-patient differences in stromal-to-epithelial ratio of prostate tissue did affect outcomes. Poor responders to TUMT seemed to have a higher vessel density and a lower epithelial/stromal ratio. Relatively more abundant epithelial cells in the prostate tissue may lead to more favorable outcomes. Use of higher energy, patients with higher grade of obstruction, younger patient age, larger prostate volume (>25 mL), and higher prostate-specific antigen levels seemed to be associated with a better response to TUMT.

New energy protocols could help tailor treatment to the individual needs of each patient. Nomograms based on volume, age, and pressure-flow parameters could assist in making clinical recommendations and identifying treatment responders; however, the total amount of energy appeared to have a high impact on the prediction of response.