Serum levels of prostate-specific antigen among Japanese-American and native Japanese men.
BACKGROUND
Fourfold to sixfold higher prostate cancer rates in Japanese-American men in the United States compared with Japanese men in Japan have been cited to support a role for environmental risk factors in the etiology of the disease. To examine the hypothesis that part or all of the elevated prostate cancer rates in Japanese-American men may reflect more intensive prostate cancer screening in the United States than in Japan, we compared prostate-specific antigen (PSA) levels in community-based samples of serum from men without prostate cancer.


METHODS
Japanese-American men aged 40-85 years and native Japanese men aged 40-89 years with no history of prostate cancer provided sera, respectively, in the United States from March 1990 through March 1992 (n = 237) or in Japan from January 1992 through December 1993 (n = 3522). Age-specific PSA levels were used to estimate the prevalences of undetected prostate cancer in the two populations.


RESULTS
Age-specific mean PSA levels were significantly lower in Japanese-Americans than in native Japanese (two-sided P<.001). The prevalence of an elevated PSA level increased with age in both populations and exceeded 5% among men aged 60 years or more. Combined with data on prevalence of detected prostate cancer in the two populations, our data suggest that some 10.0% of Japanese-Americans aged 75 years have prostate cancer, with 31% of that fraction remaining undiagnosed. The corresponding estimates in Japan are a total cancer prevalence of 5.4%, of which 81% has not been detected clinically.


CONCLUSIONS
The total cancer prevalence ratio 10.0/5.4 = 1.9 (95% confidence interval = 1.5-2.3) in Japanese-American men compared with Japanese men in Japan suggests an increased risk for Japanese-American men, but of less magnitude than the fourfold to sixfold increase indicated by the incidence data.
Shibata
A
A
Department of Health Research and Policy, Stanford University School of Medicine, CA 94305-5405, USA. shibata@osiris.stanford.edu
Whittemore
A S
AS
Imai
K
K
Kolonel
L N
LN
Wu
A H
AH
John
E M
EM
Stamey
T A
TA
Paffenbarger
R S
RS
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001213:Asian / Q000706:statistics & numerical data; D044466:Asian People; D006801:Humans; D007564:Japan / Q000453:epidemiology / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000276:immunology*; D014481:United States / Q000453:epidemiology
D017430:Prostate-Specific Antigen