| Despite a steady decrease in morbidity and mortality over the past 20 years, colorectal cancer (CRC) remained the fourth most common cancer diagnosis in 2013, and the second most common cause of cancer death. Of perhaps more importance are the substantial health disparities evident in both the incidence and mortality rates for this disease. Historically, these differences have been attributed to socioeconomic status, and, more specifically, inequality in access to healthcare, preventive practices, and treatment options. For that to be true, populations with similar socioeconomic status should have comparable colorectal cancer incidence and mortality rates. In reality, African Americans have CRC rates significantly higher than non-Hispanic whites, while Hispanic Americans have rates significantly lower than non-Hispanic whites, even though both minorities tend to be in similar socioeconomic groups, face discrimination in the healthcare industry, and participate in fewer colonoscopy screenings per year. Interestingly, while CRC has many causes, 80% of cases are considered "sporadic," and have been linked to a variety of specific behavioral risk factors, such as poor diet, inactivity, smoking, alcohol use, and obesity. These behaviors can lead to risk profiles that put an individual at greater risk for carcinogenesis. Therefore, health disparities between African Americans, Hispanic Americans and non-Hispanic whites may not be caused by socioeconomic differences per se, but may be due to cultural influences in these behavioral risk factors. This thesis addresses this issue by 1) investigating the relationship among differences in diet, smoking, physical activity, and allostatic load between African Americans, non-Hispanic whites, and Hispanic Americans and CRC incidence, 2) elucidating how these factors affect CRC-specific mortality risk later in life, 3) exploring how socioeconomic status directly and indirectly affects CRC risk among these populations, and 4) scrutinizing the possibility that a "healthy immigrant effect" in Hispanic Americans protects this population from colorectal carcinogenesis. |
