Dietary Patterns and Colon Cancer Risk in Whites and African Americans in the North Carolina Colon Cancer Study

Abstract

We examined associations of dietary patterns with colon cancer risk in African Americans and Whites from a case-control study in North Carolina. Incident colon cancer cases, 40 to 80 yr (n = 636), and matched controls (n = 1,042) were interviewed in person to elicit information on potential colon cancer risk factors. A validated food frequency questionnaire adapted to include regional foods captured diet over the year prior to diagnosis (cases) or interview date (controls). Three meaningful intake patterns were identified in both Whites and African Americans: “Western-Southern,” “fruit-vegetable,” and “metropolitan.” Compared to the Western-Southern pattern, the fruit-vegetable and metropolitan patterns were associated with more healthful dietary behaviors (e.g., higher vegetable intake and lower red meat consumption), and demographic/lifestyle characteristics typically correlated with low colon cancer risk, for example, lower BMI, higher education, and higher NSAID use. The fruit-vegetable pattern was significantly inversely associated with colon cancer risk in Whites (OR = 0.4, 95% CI = 0.3–0.6) and the metropolitan pattern with a nonsignificant 30% risk reduction in both Whites and African Americans after adjustment for education. The Western-Southern pattern was not associated with colon cancer risk. These findings may explain some of the racial differences in colon cancer incidence and underscore the importance of examining diet-cancer associations in different population subgroups.

ACKNOWLEDGMENTS

This research was funded by the following grants from the National Institutes of Health: Grant numbers K22 CA96556, R01 CA 66635, and P30 DK 34987.

Notes

^a Abbreviations are as follows: BMI, body mass index; MET, metabolic equivalent task; NSAID, nonsteroidal anti-inflammatory drug.

* P < 0.01.

** P < 0.05.

^a N = 478.

^b N = 478.

^a N = 361.

^b N = 361.

^a Abbreviations are as follows: BMI, body mass index; MET, metabolic equivalent task; NSAID, nonsteroidal anti-inflammatory drug; TE, tocopherol equivalents.

^b Two asterisks

(**) means the P value comparing tertiles 1 and 3 is < 0.01. One asterisk

(*) means the P value comparing tertiles 1 and 3 is

^c Calculated as residual from model with both cases and controls plus mean unadjusted value for controls. Because the numbers are energy adjusted, it is possible for the numbers to be negative; however, the P value for the comparisons are still valid.

^a Abbreviations are as follows: BMI, body mass index; MET, metabolic equivalent task; NSAID, nonsteroidal anti-inflammatory drug; TE, tocopherol equivalents.

^b Two asterisks

(**) means the P value comparing tertiles 1 and 3 is < 0.01. One asterisk

(*) means the P value comparing tertiles 1 and 3 is < 0.05.

^c Calculated as residual from model with both cases and controls plus mean unadjusted value for controls. Because the numbers are energy adjusted, it is possible for the numbers to be negative; however, the P value for the comparisons are still valid.

^a Models adjusted for age, sex, total energy intake, and offset term. Abbreviation is as follows: Ref, reference.

^b Models adjusted for preceding variables and education, first-degree family history of colon cancer, physical activity, vitamin/mineral use, and body mass index 1 yr ago for Pattern 1, none for Pattern 2, and education for Pattern 3.

^c P value for trend was obtained for each pattern by including the tertile variable in the model as a continuous term.

^a Models adjusted for age, sex, total energy intake, and offset term. Abbreviation is as follows: Ref, reference.

^b Models adjusted for preceding variables and education, first-degree family history of colon cancer, physical activity, vitamin/mineral use, and BMI 1 yr ago for Pattern 1, none for Pattern 2, and education for Pattern 3.

^c P value for trend was obtained for each pattern by including the tertile variable in the model as a continuous term.