Microwave treatment effect on prostate cancer

A recent column was devoted to answering a question posed by a caller regarding the effect of transurethral microwave thermotherapy on the prostate. He wanted to know whether or not having such a treatment would in some way alter the cellular nature of the prostate so that at some future time, a pathologist, examining a biopsy of a prostate so treated might not be able to properly make a diagnosis of prostate cancer in a timely fashion. A thorough search of the literature left no doubt that there need be no such concern.

One article however, jointly conducted by the Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, Department of Urology, Mayo Clinic, Scottsdale, Arizona, and Universidad Nacional de Cuyo, Mendoza, Argentina brought to light some interesting points on the effect of microwave thermotherapy on prostate cancer. This article entitled “Does Transurethral Microwave Thermotherapy Have A Different Effect On Prostate Cancer Than On Benign Or Hyperplastic Tissue?” was reported in UROLOGY 54: 67-72, 1999. In this study, patients with known cancer of the prostate, proven on biopsy and who were considered good candidates for radical prostate cancer surgery were first treated with microwave thermotherapy and thereafter underwent the radical prostate cancer surgery. The time interval between the thermotherapy and the surgery varied mostly from four hours to four days and a small number of patients had the radical surgery performed 12 months after the thermotherapy. The entire prostate specimens removed at surgery were analyzed to evaluate what effect the thermotherapy had on the cancer contained within each prostate.

The conclusion was that microwave thermotherapy was equally effective in destroying benign prostate tissue, hyperplastic tissue and cancer tissue. Where the microwaves reached the cancer, the cancerous tissue was destroyed. Since in four out of five cases, cancer occurs in the periphery of the prostate and microwaves are mostly effective in the interior portion of the prostate near the urethra, thermotherapy cannot reach cancerous tissue located in the peripheral regions of the prostate. However, when the microwaves did reach cancerous tissue, that portion of the cancer that was reached was destroyed.

In the patients who underwent radical prostate surgery a year after the microwave thermotherapy, the cancer found in the surgical specimen was identical to the cancer found in the pretreatment biopsy. There was no significant change in Gleason Scores from before microwave thermotherapy to after microwave thermotherapy. The Gleason Score is the pathologist’s way of describing the degree of malignancy of a particular prostate cancer and that will be the topic for a future column. Of particular interest was their conclusion that transurethral microwave thermotherapy may, in selected patients have palliative value in shrinking or debulking prostate cancer that obstructs the outflow of urine. This should not be considered a curative therapy for cancer.

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