The association between dietary factors and risk of rectal cancer in African Americans and Whites Public Deposited

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  • March 21, 2019
  • Williams, Christina Dawn
    • Affiliation: Gillings School of Global Public Health, Department of Nutrition
  • Colorectal cancer (CRC), a commonly diagnosed malignancy in the U.S., refers to cancers of the colon and rectum. African-Americans have the highest incidence and mortality rates for CRC; many reasons for this disparity remain unknown. Diet is involved in the etiology of CRC. There is an abundance of literature on diet and CRC or colon cancer, while evidence is limited on the role of diet in rectal cancer specifically. This dissertation addresses these issues by examining the relationship between dietary factors and rectal cancer risk, and determining if these associations differ between whites and African-Americans. We used the North Carolina Colon Cancer Study-Phase II, which included 945 rectal cancer cases (including sigmoid and rectosigmoid) and 959 controls. The Diet History Questionnaire was used to assess dietary intake, and we examined the following dietary factors: macronutrients, micronutrients, food groups, and dietary patterns. For macronutrients, we observed no association between fat intake in whites or African-Americans; only a possible risk reduction in African-Americans with high intake of polyunsaturated fatty acids. In whites, protein (% energy) was associated with lower rectal cancer risk. In regards to the micronutrients, statistically significant inverse associations were observed in whites for most micronutrients, but only for selenium in African-Americans. Interestingly, micronutrient intake from dietary supplements did not provide additional risk reduction. Regarding food groups, non-whole grains and white potatoes appeared to elevate rectal cancer risk in whites, while fruits, vegetables, dairy, fish, and poultry were inversely related to risk. In African-Americans, high fruit intake was positively associated with risk for rectal cancer. We identified three dietary patterns in whites and African-Americans. The High fat/Meat/Potatoes pattern was similar in both race groups, and associated with elevated risk in whites. This work adds to the literature on the relationship between diet and rectal cancer, and suggests that these associations differ by race. It also provides information on the epidemiology of rectal cancer in African-Americans, for which evidence is lacking. Rectal cancer is preventable, partially by dietary modifications; therefore, it is necessary to examine the role of diet in the etiology of rectal cancer, especially in large racially diverse samples.
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  • In Copyright
  • Satia, Jessie
Degree granting institution
  • University of North Carolina at Chapel Hill
  • Open access

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