Cancer de la prostate

With more emphasis on breast cancer screening now the norm, the spotlight has moved to prostate cancer screening in men, with some physician groups firmly in favor of annual screening for all men in the 50 to 70 age group and others claiming that the money could be better spent on finding out more about the disease and causative factors.

The American College of Physicians (Philadelphia, Pennsylvania) has come out against routine testing for prostate cancer. Peter Albertsen, MD, a noted urologist at the University of Connecticut Health Center (Farmington, Connecticut), argues that mass screening, besides being expensive, will result in thousands of unnecessary operations. Albertsen estimates that a nationwide screening program could cost anywhere from $12 billion to $28 billion in the first year alone.

Prostate cancer is generally a disease of older men, and since it is a slow developer, a majority of those with prostate tumors die with them rather than of them. James Hanley and Maurice McGregor of the Consell d'Evaluation des Technologies de la Sante in Quebec, Canada, estimate that for every fatal prostate tumor detected in a screening program, another five will be found which could readily be left untouched. This does not take into account the reactions of patients diagnosed as being tumorigenic; many would be unlikely to leave the tumor alone. A survey by Britain's National Health Service indicates that radical prostatectomy causes incontinence in up to 27% of patients and impotence in close to 85% of them. Radiotherapy figures are significantly better: 6% for incontinence and 40% for impotence, although newer methodologies such as radioactive pellet implantation have reportedly produced better outcomes.

Endoscopic surgical procedures for prostate cancer and cryotherapy techniques have been used successfully. Gunnar Aus, of the Department of Urology at Ostra Hospital (Goteborg, Sweden), has evaluated results on a group of 29 prostate cancer patients treated by cryotherapy with two complete freeze-thaw cycles. In 24 patients, serum PSA was [less than]0.5ng/ml, with 6 of 8 biopsied patients having negative biopsies.

Albert Gelet and his team at Edouard Herriot Hospital (Lyon, France) have reported the use of the Ablatherm system for transrectal, focused high-intensity ultrasound from Technomed Medical Systems (Bron, France), with 50% of patients showing no residual cancer on biopsy investigations.

Robert Hillenius and his group at University Hospital (Utrecht, the Netherlands) have experimentally used photodynamic therapy (PDT) with intravenous administration of tin-ethyl-etiopurpurinel (SnE[T.sup.2]) and subsequent transurethral monochromatic light diffusion. Results in canine prostates have confirmed the feasibility of PDT using SnE[T.sup.2] as a safe and effective treatment for the benign or cancerous prostate.

Further developmental work on the use of PDT for early-stage prostate cancer treatment is continuing at the National Medical Laser Center of the University College of London Medical School (London). Professor Stephen Brown, head of the center, said that the first five patients who had undergone the procedure were still under evaluation. General use of PDT for early-stage prostate cancer would enable the procedure to be carried out in most cases on an ambulatory basis. In turn, that would increase pressure for a national screening service using PSA blood tests.

Boehringer Mannheim (Martaheim, Germany) is developing a reverse-transcriptase PCR assay for prostate-specific membrane antigen, while Hybritech (San Diego, California) is developing an in vitro ELISA test. The antigen, which was developed by Cytogen (Princeton, New Jersey), is used in its ProstaScint imaging agent, which obtained FDA clearance in November 1996.