Dietary manipulation, ethnicity, and serum PSA levels.
OBJECTIVE
To examine whether a diet low in fat and high in fiber, fruits, and vegetables and ethnicity had any influence on serum prostate-specific antigen (PSA) levels, because serum PSA is a marker for the presence of prostate cancer. The incidence of prostate cancer increases with age, varies by ethnicity, and is greater among men with a first-degree relative who has had the disease. Large international variations in the rates of prostate cancer incidence and mortality, as well as the incidence changes in migrants and their offspring, also suggest that exogenous factors, including diet, have a strong influence on the development of this disease.


METHODS
We used data and blood samples from the Polyp Prevention Trial, a multicenter randomized trial designed to evaluate the impact of a diet low in fat and high in fiber, fruits, and vegetables on the recurrence of colorectal adenomas. Recruitment was from 1991 through 1994. Participants were followed up from their baseline recruitment date for 4 years. From this group, we identified 1100 white men and 97 black men who were 35 years of age or older, did not have prostate cancer, and had serum samples available for study.


RESULTS
At baseline, no difference was present in the fat intake for the black and white men (mean +/- SE, 90 +/- 3.6 g/day and 84 +/- 1.0 g/day, respectively; P = 0.15). The baseline serum PSA levels did not vary by ethnicity. For black men, the mean serum PSA level was 2.2 +/- 0.36 ng/mL compared with 2.0 +/- 0.07 ng/mL for white men (P = 0.64). Although all men assigned to the intervention group markedly reduced their fat intake by approximately 15% and increased their fruit and vegetable intake by approximately 2.25 servings per day, no difference was noted in the kinetics of the serum PSA levels by dietary intervention or race.


CONCLUSIONS
Although ethnic differences in the incidence of prostate cancer are well defined, we found no difference in the baseline fat intake among black and white men that might have contributed to this difference. Serum PSA, a marker often used in early detection programs for prostate cancer, was not associated with manipulation of the amount of fat in the diet, regardless of ethnicity.
Eastham
James A
JA
Department of Urology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Riedel
Elyn
E
Latkany
Lianne
L
Fleisher
Martin
M
Schatzkin
Arthur
A
Lanza
Elaine
E
Shike
Moshe
M
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D044383:Black People; D015331:Cohort Studies; D018752:Diet, Fat-Restricted; D004041:Dietary Fats / Q000009:adverse effects; D004043:Dietary Fiber / Q000008:administration & dosage; D005006:Ethnicity; D005247:Feeding Behavior; D005500:Follow-Up Studies; D005638:Fruit; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control; D014481:United States / Q000453:epidemiology; D014675:Vegetables; D044465:White People; D001741:Black or African American
D014408:Biomarkers, Tumor; D004041:Dietary Fats; D004043:Dietary Fiber; D017430:Prostate-Specific Antigen