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
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.