Samantha Streicher

Behavioral, Lifestyle, and Genetic Risk Factors of Colorectal Cancer: a Case-Control Study in Tel Aviv, Israel

ABSTRACT: Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second leading cause of cancer mortality in the western world. CRC tumorigenesis involves a multistep process beginning with the formation of an adenoma that can ultimately develop into carcinoma. Risk factors for CRC have been extensively studied in Israel since approximately 6% of the Ashkenazi Jewish population carries the I1307K mutation on the APC gene, predisposing this population to CRC. Furthermore, multiple risk factors of CRC are modifiable and can be altered to lower the risk of CRC. To investigate the relationship between lifestyle, behavioral, and genetic risk factors and CRC, we examined data on body mass index (BMI), leisure-time physical activity, CD24 genotype, ethnic origin, and smoking status collected from the Integrated Cancer Prevention Center in Tel Aviv, Israel from 2000-2007. In this analysis, we did a frequency matched case control study with 180 CRC patients and 720 controls. Information about lifestyle and behavior risk factors was obtained from a questionnaire, while genotyped DNA was used to assess genetic risk factors. Proc means and proc freq were used to evaluate the distribution of continuous and categorical variables in the total population, cases, and controls. Proc logistic was used to assess the univariate models and to investigate confounding and interaction for the multivariable model. We were especially interested in the relationship between CRC and a novel polymorphism in the CD24 gene, CD24VV and CD24AV. BMI, ethnic origin, and smoking status were found to be modestly associated with CRC in the multivariable model: the odds ratios were 1.05 (95% CI: 1.02, 1.09), 1.51 (95% CI: 1.03, 2.21), and 1.40 (95% CI: 1.00, 1.97), respectively. Furthermore, smoking status was found to modify BMI: the odds ratios were 1.10 (95% CI: 1.04, 1.17) for ever smoked and 1.03 (95% CI: .97, 1.08) for never smoked. Although the CD24 polymorphism was not found to have a significant relationship with CRC, several significant relationships were found that were consistent with risk factor literature on CRC. 

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