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

Sammanfattning: Transurethral microwave thermotherapy of benign prostatic hyperplasia- a clinical and methodological evaluation Anders Hallin, Department of Urology, Karolinska Institutet, HuddingeUniversity Hospital, S-14186 Huddinge, Sweden Transurethral microwave thermotherapy (TUMT) is a relatively new type of treatmentfor symptomatic benign prostatic hyperplasia. The aim of this study was to evaluatedifferent 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 theperformance of each catheter was described (Paper I). The design of a catheter significantlyaffects the heating profile, but its influence on the results of treatment is notknown. In the follow-up studies, the patient's subjective opinion about treatment resultwas used to classify him as a responder or non-responder. In the group of patientsevaluated 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 afterone 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, followedby a significant decrease in flow rate at the four-year follow-up. Residual urinewas not affected during the follow-ups. No pretreatment parameters were helpful inpredicting the outcome. There appeared to be a subjectively better response in menwho 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 theprostate and clinical response was found. No significant changes were seen in theprostate six months after treatment. An explanation of the underlying mechanism ofthe effect of TUMT might be a denervation rather than a loss of tissue in the prostateadenomas. In the analysis of androgen status (Paper V), non-responders had a higher testosteronelevel than responders before treatment. A higher degree of androgen stimulation mightmake an androgen-sensitive tissue, such as the prostate, more resistant to treatmentsinducing partial destruction, such as TUMT. The study of semen was difficult to carry out (Paper VI), mainly because the patientshad difficulties in providing semen samples at the hospital. Only one sample beforeand one after TUMT treatment could therefore be collected from the patients willingto participate. No statistically signif;cant changes were seen in sperm counts, fructoseor 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 affectthe results, further studies of the equipment for treatment are needed. Apart froma low testosterone level, no predictive variables for a positive treatment resultwere found. No permanent changes were detected in prostate adenomas with MRI. Theeffect of TUMT on semen emission needs further studies. Key words: benign prostatic hyperplasia, microwave thermotherapy, long-termfollow-up, MRI, semen, androgen. ISBN-9 1 -628-2727-8