More Evidence of Link Between Diet, Prostate Cancer

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

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

The 20 intervention patients were given a dietary plan consisting of20% of total calories from dietary fat as well as high levels of dietaryfiber, fruits, and vegetables. Counseling and compliance were assessedduring frequent visits with the study nutritionist.

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

Speaking at a poster session, Neil Fleshner, MD, MPH, said that amongthe 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 increasedin eight (21%). Serum testosterone levels were not altered by the dietaryplan.

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

Role of Selenium

In a separate presentation, a multicen-ter trial based at seven dermatologyclinics showed that selenium supplementation had a protective effect againstprostate cancer. The placebo-controlled Nutritional Prevention of CancerTrial followed 974 patients who had a history of skin cancer, randomizingthem to receive 200 micrograms of selenium or placebo during the time period1983 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 groupvs 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.