Transurethral microwave thermotherapy of benign prostatic hyperplasia : a clinical and methodological evaluation

Transurethral microwave thermotherapy (TUMT) is a relatively new type of treatment for symptomatic benign prostatic hyperplasia. The aim of this study was to evaluate different aspects of TUMT such as catheter characteristics, morphological changes, effects on hormones and semen emission as well as to assess long-term treatment outcome.Patients treated with TUMT between 1991 and 1994 were admitted to the various studies.The clinical outcome was analysed with both objective and subjective parameters. Three types of TUMT equipment and their treatment catheters were studied and the performance of each catheter was described (Paper I). The design of a catheter significantly affects the heating profile, but its influence on the results of treatment is not known. In the follow-up studies, the patient's subjective opinion about treatment result was used to classify him as a responder or non-responder. In the group of patients evaluated after one year 56% were classified as responders at follow-up (Paper II).In the four-year follow-up study 62% were satisfied with the treatment result after one year but only 23% were classified as responders after four years (Paper III).A tendency to an increase in peak urinary flow rate was seen after one year, followed by a significant decrease in flow rate at the four-year follow-up. Residual urine was not affected during the follow-ups. No pretreatment parameters were helpful in predicting the outcome. There appeared to be a subjectively better response in men who were objectively less in need of a response. To analyse changes in the prostate tissue in vivo, magnetic resonance imaging(MRI) was used (Paper IV). A weak correlation between posttreatment oedema in the prostate and clinical response was found. No significant changes were seen in the prostate six months after treatment. An explanation of the underlying mechanism of the effect of TUMT might be a denervation rather than a loss of tissue in the prostate adenomas. In the analysis of androgen status (Paper V), non-responders had a higher testosterone level than responders before treatment. A higher degree of androgen stimulation might make an androgen-sensitive tissue, such as the prostate, more resistant to treatments inducing partial destruction, such as TUMT. The study of semen was difficult to carry out (Paper VI), mainly because the patients had difficulties in providing semen samples at the hospital. Only one sample before and one after TUMT treatment could therefore be collected from the patients willing to participate. No statistically significant changes were seen in sperm counts, fructose or zinc levels. However, one patient developed azoospermia after TUMT. In conclusion, the long-term results of TUMT treatment of symptomatic benign prostatichyperplasia are not impressive. However, since differences in catheters may affect the results, further studies of the equipment for treatment are needed. Apart from a low testosterone level, no predictive variables for a positive treatment result were found. No permanent changes were detected in prostate adenomas with MRI. The effect of TUMT on semen emission needs further studies.