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More Evidence of Link Between Diet, Prostate Cancer

More Evidence of Link Between Diet, Prostate Cancer

NEW ORLEANS--More evidence that diet may affect prostate cancer came from two presentations at the American Urological Association annual meeting.

In a study from Memorial-Sloan Kettering, patients who reduced their dietary fat had a reduction in serum PSA levels. This dietary modification trial included 58 men with elevated PSA levels (over 4 ng/mL) and two negative transrectal ultrasound-guided biopsies (including transition zone assessment).

The 20 intervention patients were given a dietary plan consisting of 20% of total calories from dietary fat as well as high levels of dietary fiber, fruits, and vegetables. Counseling and compliance were assessed during frequent visits with the study nutritionist.

Both the patients on the diet and the 38 controls were followed for one year, and changes in serum PSA of 15% were considered significant.

Speaking at a poster session, Neil Fleshner, MD, MPH, said that among the 20 intervention patients, serum PSA levels decreased in 12 men (60%), did not change in three (15%), and increased in five (25%). In the 38 controls, levels decreased in seven (18%), did not change in 23 (61%), and increased in eight (21%). Serum testosterone levels were not altered by the dietary plan.

Some patients responded dramatically to the diet; for example, one patient had a baseline PSA of 8.8 ng/mL, which dropped to 6.7 at six months and leveled off at 4.3 at 12 months, for a 51% decline. Dr. Fleshner said he does not know if the PSA decrease will significantly affect the prostate epithelium, but he plans to study the biopsy material.

Role of Selenium

In a separate presentation, a multicen-ter trial based at seven dermatology clinics showed that selenium supplementation had a protective effect against prostate cancer. The placebo-controlled Nutritional Prevention of Cancer Trial followed 974 patients who had a history of skin cancer, randomizing them to receive 200 micrograms of selenium or placebo during the time period 1983 to 1996.

The incidence of nonmelanoma skin cancer was not affected by the intervention, but 60 cases of prostate cancer were diagnosed: 41 in the placebo group vs 19 in the selenium group during the 7,537 man-years of observation. This was a significant 54% reduction in incidence of prostate cancer, Dr. Larry Clark, of the Arizona Cancer Center, reported.

 
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