BERKELEY, CA (UroToday.com) - The high incidence of prostate cancer in Western Europe and North America suggests that prostate cancer is related to a “Western” life-style or environment. The incidence of prostate cancer increased drastically during the mid to late 90s, mainly due to better diagnostic techniques, especially by testing of serum levels of prostate-specific antigen (PSA). The aim of the current study was to assess the association between metabolic factors, singly and combined, and risk of diagnosis and death from prostate cancer, using a cohort of almost 290 000 European men.[1]
We conducted a study within the Metabolic Syndrome and Cancer Project (Me-Can) with prospectively collected data on body mass index (BMI), blood pressure, and blood levels of glucose, cholesterol, and triglycerides in cohorts in Norway, Sweden, and Austria.[2] Cox proportional hazard models were used to calculate relative risks (RRs) of prostate cancer by exposures divided in quintiles and transformed to z-scores (with mean 0 and standard deviation 1), together with a composite sum of scores to assess combined effect of metabolic factors. RRs were corrected for random errors, i.e., measurement error and fluctuation over time. To investigate if associations differed according to calendar period at diagnosis, we performed subgroup analysis for follow-up ending in December 31, 1996, and starting in January 1, 1997, respectively. The cut point was selected at a date when a strong increase in use of PSA testing commenced in these populations.
During follow-up, 6 673 men were diagnosed with prostate cancer and 961 men died from prostate cancer. We found no associations between high levels of metabolic factors and risk of prostate cancer (Figure 1a), but high BMI, blood pressure, and a high composite z-score of all metabolic factors combined were associated with increased risk of prostate cancer death (Figure 1b). In subgroup analysis according to calendar period, all metabolic factors and the composite score were more strongly associated with risk among men diagnosed before December 31, 1996 (Figure 2). During the early calendar period, a large proportion of men diagnosed with prostate cancer were at an advanced stage of the disease. In contrast, during the later calendar period, i.e., during the PSA testing era, high levels of metabolic factors were inversely associated with risk of prostate cancer.
In conclusion, we found no evidence of an association between high levels of metabolic factors and risk of prostate cancer, but high levels of BMI, blood pressure, and a composite score of all metabolic factors were associated with prostate cancer death. There were stronger associations to metabolic factors for men diagnosed before 1997, suggesting that there is an association between metabolic factors and aggressive/advanced disease.
Funding for the Me-Can project was obtained from the World Cancer Research Fund (2009/247) and the Swedish Cancer Foundation (2010/628).
Figure 1
Figure legend:
Model 1: Cox regression models adjusted for smoking and stratified for sub cohort, five birth cohorts and five categories of age at measurement. Correction for random error was done by use of regression dilution ratio, original values for each variable can be obtained by: RRoriginal=elog(RRcorrected)*RDR. RDR for BMI=0.899, Blood pressure=0.528, Glucose (log)=0.283, Cholesterol=0.644, Triglycerides (log)=0.512, Composite score=0.677.
Model 2: Cox regression models adjusted for smoking, stratified for sub cohort, five birth cohorts and five categories of age at measurement and also adjusted for z-scores of all separate metabolic exposures. Correction for random error was made by regression calibration.
Figure 2
Figure legend:
Cox regression models adjusted for smoking and stratified for sub cohort, five birth cohorts and five categories of age at measurement, one model with end of follow up at December 31, 1996 and a second model with start of follow up at January 1, 1997. Correction for random error was done by use of regression dilution ratio, original values for each variable can be obtained by: RRoriginal=elog(RRcorrected)*RDR. RDR for BMI=0.899, Blood pressure=0.528, Glucose (log)=0.283, Cholesterol=0.644, Triglycerides (log)=0.512, Composite score=0.677.
References:
- Haggstrom, C., et al., Prospective study on metabolic factors and risk of prostate cancer. Cancer, 2012.
- Stocks, T., et al., Cohort Profile: The Metabolic syndrome and Cancer project (Me-Can). Int J Epidemiol, 2010. 39(3): p. 660-7.
Written by:
Christel Häggström,a Tanja Stocks,a, b and Pär Stattina, c as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
- Department of Surgical and Perioperative sciences, Urology and Andrology, Umeå University, Umeå, Sweden
- Institute of Preventive Medicine, Frederiksberg Hospital, Frederiksberg, Denmark
- Department of Surgery, Urology Service, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
Prospective study on metabolic factors and risk of prostate cancer - Abstract
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