Body Mass Index, Weight Change, and Risk of Prostate Cancer in the Cancer Prevention Study II Nutrition Cohort
Written by Ricardo Sanchez-Ortiz, MD
Thursday, 15 February 2007
BERKELEY, CA (UroToday.com) – In the last five years, a large body of evidence has been accumulated supporting the association between obesity and high-risk prostate cancer.
Despite this advancement in our knowledge of prostate carcinogenesis, the exact interplay between BMI and patient risk remains poorly understood.
In the January issue of Cancer Epidemiology, Biomarkers, Rodríguez and colleagues from the American Cancer Society report data from the Cancer Prevention Study II Nutrition Cohort evaluating the relationship between obesity and prostate cancer risk. Beside its large size, this study is newsworthy because it substratified prostate cancer patients based on tumor grade and stage.
The cohort consisted of 69,991 men who registered information on height and weight at enrollment (year 1982) and were followed for 20 years. Patients with an elevated BMI exhibited a lower risk for non-metastatic low grade prostate cancer (risk ratio: 0.84), but demonstrated a higher trend for being diagnosed with nonmetasteatic high grade prostate cancer (risk ratio: 1.22, 95% CI 0.96 to 1.55) and a higher risk for dying of metastatic prostate cancer (risk ratio: 1.54, 95% CI 1.06 to 2.23). Interestingly, those men with a registered weight loss of greater than 11 pounds (in the first 10 years of the study) were found to have a significantly decreased risk of developing nonmetastatic high-grade prostate cancer (RR: 0.58, 95% CI 0.42 to 0.79).
These data from a large, prospective, epidemiological study suggest that patients with an elevated BMI are less likely to develop low grade prostate cancer and more likely to develop high grade prostate cancer. This dichotomous distribution in risk may partly explain why studies that have not substratified patients based on tumor grade had not found an association between obesity and prostate risk. Furthermore, perhaps the most compelling argument in favor of this increased risk was the documented risk reduction in high grade prostate cancer with dietary modification and weight loss.
Carmen Rodriguez, Stephen J. Freedland, Anusila Deka, Eric J. Jacobs, Marjorie L. McCullough, Alpa V. Patel, Michael J. Thun, and Eugenia E. Calle
Cancer Epidemiol Biomarkers Prev.;16(1):63-9.
UroToday.com Prostate Cancer Section