Body mass index and incidence of localized and advanced prostate cancer--a dose-response meta-analysis of prospective studies.
BACKGROUND
The relationship between obesity and risk of prostate cancer (PCa) is unclear; however, etiologic heterogeneity by subtype of PCa (localized, advanced) related to obesity was suggested. Therefore, we conducted a dose-response meta-analysis of prospective studies to assess the association between body mass index (BMI) and risk of localized and advanced PCa.


METHODS
Relevant prospective studies were identified by a search of Medline and Embase databases to 03 October 2011. Twelve studies on localized PCa (1,033,009 men, 19,130 cases) and 13 on advanced PCa (1,080,790 men, 7067 cases) were identified. We carried out a dose-response meta-analysis using random-effects model.


RESULTS
For localized PCa, we observed an inverse linear relationship with BMI [Ptrend<0.001, relative risk (RR): 0.94 (95% confidence interval, 95% CI, 0.91-0.97) for every 5 kg/m2 increase]; there was no evidence of heterogeneity (Pheterogeneity=0.27). For advanced PCa, we observed a linear direct relationship with BMI (Ptrend=0.001, RR: 1.09 (95% CI 1.02-1.16) for every 5 kg/m2 increase); there was weak evidence of heterogeneity (Pheterogeneity=0.08). Omitting one study that contributed substantially to the heterogeneity yielded a pooled RR of 1.07 (95% CI 1.01-1.13) for every 5 kg/m2 increase (Pheterogeneity=0.26).


CONCLUSIONS
The quantitative summary of the accumulated evidence indicates that obesity may have a dual effect on PCa-a decreased risk for localized PCa and an increased risk for advanced PCa.
Nutritional Epidemiology Unit, Division of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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Discacciati
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Orsini
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Wolk
D015992:Body Mass Index; D006801:Humans; D015994:Incidence; D008297:Male; D060787:Neoplasm Grading; D009765:Obesity / Q000150:complications* / Q000453:epidemiology / Q000473:pathology; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D012307:Risk Factors