Obesity, diabetes, and risk of prostate cancer: results from the prostate cancer prevention trial.
Studies on the relationship between obesity and prostate cancer incidence are inconsistent. In part, this inconsistency may be due to a differential effect of obesity on low-grade and high-grade cancer or confounding of the association of obesity with prostate cancer risk by diabetes. We investigated the associations of obesity and diabetes with low-grade and high-grade prostate cancer risk. Data were from 10,258 participants (1,936 prostate cancers) in the Prostate Cancer Prevention Trial who all had cancer presence or absence determined by prostate biopsy. Multiple logistic regression was used to model the risk of total prostate cancer, and polytomous logistic regression was used to model the risk of low-grade and high-grade prostate cancer. Compared with men with body mass index < 25, obese men (body mass index > or =30) had an 18% [odds ratio (OR), 0.82; 95% confidence interval (95% CI), 0.69-0.98] decreased risk of low-grade prostate cancer (Gleason <7) and a 29% (OR, 1.29; 95% CI, 1.01-1.67) increased risk of high-grade prostate cancer (Gleason > or =7) or, alternatively, a 78% (OR, 1.78; 95% CI, 1.10-2.87) increased risk defining high-grade cancer as Gleason sum 8 to 10. Diabetes was associated with a 47% (OR, 0.53; 95% CI, 0.34-0.83) reduced risk of low-grade prostate cancer and a 28% (OR, 0.72; 95% CI, 0.55-0.94) reduced risk of high-grade prostate cancer. Associations of obesity or diabetes with cancer risk were not substantially changed by mutually statistical controlling for each other. Obesity increases the risk of high-grade but decreases the risk of low-grade prostate cancer, and this relationship is independent of the lower risk for prostate cancer among men with diabetes.
Gong
Zhihong
Z
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North M4-B402, Seattle, WA 98109-1024, USA. zgong@fhcrc.org
Neuhouser
Marian L
ML
Goodman
Phyllis J
PJ
Albanes
Demetrius
D
Chi
Chen
C
Hsing
Ann W
AW
Lippman
Scott M
SM
Platz
Elizabeth A
EA
Pollak
Michael N
MN
Thompson
Ian M
IM
Kristal
Alan R
AR
D000230:Adenocarcinoma / Q000150:complications / Q000453:epidemiology* / Q000473:pathology / Q000517:prevention & control*; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D003920:Diabetes Mellitus / Q000453:epidemiology*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D018120:Finasteride / Q000627:therapeutic use; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D011471:Prostatic Neoplasms / Q000150:complications / Q000453:epidemiology* / Q000473:pathology / Q000517:prevention & control*; D012107:Research Design; D012307:Risk Factors; D049629:Waist-Hip Ratio
D004791:Enzyme Inhibitors; D018120:Finasteride