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Nov. 26, 2001 |
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n Lung n Breast n General n Prostate n Leukemia n Lymphoma n Colon n News/Issues |
High energy waves used to zap prostate cancer SEATTLE -- Nov. 26, 2001 -- Can microwaving prostate tumors kill them without harming nearby tissue? Researchers think the approach can work and early results of clinical trial are promising. The treatment approach called thermotherapy uses a special tool that focuses microwaves at the prostate tumor to raise the temperature of the cancer cells to level that kills them without damaging nearby healthy tissue. A research team led by Dr. Michael Sherar of the Medical Physics Division at the Ontario Cancer Institute in Canada published the results of a small clinical trial in the Nov. 2001 Journal of Urology. "Experience with 25 patients, in whom external beam radiation had failed, indicates that the treatment is safe," the researchers concluded. "Although our series (of patients) indicates that this therapy may be effective, further studies and longer follow-up are required in larger patient groups to confirm the potential role of this therapy as an option for recurrent and primary prostate cancer." The study involved 25 men with proven prostate cancer who had failed to respond to external beam radiation. While maintaining a saltwater block to protect the rectum and other nearby tissue, the researchers used a special coil designed to deliver microwave energy to the specific areas of the prostate containing cancer cells. They then raised the temperature to 55 degrees Centigrade (131 degrees Fahrenheit) while keeping temperatures in the urinary tract (urethra) and rectum at a safe 42 degrees C (107 degrees F). The procedure required 2.5 hours of operating time, on average. Each patient underwent PSA measurement, urinanalysis and digital rectal exams at 4-, 8-, 12- and 24-week intervals. A tissue sample was also taken from the prostate and examined under a microscope (biopsy) after 24 weeks. The researchers found that they could reliably raise the temperature of the targeted tissue to 55 degrees C, while maintaining nearby tissues at a safe 42 degrees F. After 24 weeks, PSA levels had been reduced to .5ng/ml in 52 percent of the patients, indicating that the cancer was gone. An additional 40% of patients had PSA levels between 0.51 and 4 ng/mL. The biopsies showed that 64 percent of the patients had no traces of tumor remaining. No major complications occurred and in most cases the bad side effects resolved themselves within 3 months. A quarter of the patients (24 percent) experienced temporary loss of bladder control (urinary incontinence), 12 percent experienced bladder outlet obstruction and 28 percent experienced painful bowel movements. The average time of the procedure was 2.5 hours. Writing in an accompanying editorial, Dr. Daniel Culkin of the University of Oklahoma Health Sciences Center said that "Although the technique has less complications than reported series of salvage radical prostatectomy (surgical removal of prostate and nearby tissues) they are still significant and the "true risks and benefit ratios" will only be know with longer followup. The failure rate is at least 24 percent at 1 year and will surely increase with time. The short term results may be no better than those obtained with androgen deprivation (hormone) therapy." |
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