Mediating effects of cancer risk factors on the association between race and cancer incidence: analysis of the NIH-AARP Diet and Health Study

Abstract

INTRODUCTION Racial disparities exist in both the prevalence of cancer-related risk factors and incidence of cancer. The objective of this study is to determine if cancer-related risk factors mediate the association between race and cancer incidence. METHODS We performed a prospective cohort analysis using data National Institutes of Health-American Association of Retired Persons (NIH-AARP) Diet and Health Study, years 1995 through 2011. We compared differences in baseline characteristics between Black and White participants using Chi-Square tests and Wilcoxon tests, as appropriate. We determined risk of any cancer and the most common cancer types (i.e., breast, prostate, and colorectal) using Cox Proportional hazards models, adjusted for age, sex, marital status, education, health status, region, and adherence to guidelines on cancer-related risk factors (i.e., BMI, smoking status, physical activity, nutrition, and alcohol consumption). We examined the mediation effect of cancer-related risk factors on the association between race and cancer incidence. RESULTS Among 425,152 participants, 16,110 (3.79%) were Black, and 409,042 (96.21%) were White. White participants were more likely to be aged 65 and older (35.33% vs. 25.93%), male (60.88% vs. 42.67%), married (70.37% vs. 48.26%), reside in the West (30.14% vs. 23.88%), be physically active (46.72% vs. 41.94%), and have higher adherence scores (3.14 vs. 3.04). Blacks had reduced risk of breast cancer (adjusted HR: 0.82, 95% CI: 0.74 – 0.90), but higher risk of prostate (adjusted HR: 1.86, 95% CI: 1.75 – 1.98) and colorectal (adjusted HR: 1.17, 95% CI: 1.05 – 1.31) compared with Whites. Nutrition mediated the association between race and breast cancer (6.35% mediated, p <0.01), while BMI mediated the association between race and colorectal cancer (7.99% mediated, p <0.01). CONCLUSIONS Blacks were at reduced risk of breast cancer but increased risks for prostate and colorectal cancer incidence. Nutrition and BMI exerted small, but significant mediating effects on the racial disparity in risk of breast and colorectal cancer, respectively.

Neighborhood Disadvantage, African Genetic Ancestry, Cancer Subtype, and Mortality Among Breast Cancer Survivors

“…Associations between nSES and mortality attenuated following adjustment for potential mediators, including individual SES, behavioral factors, and comorbidities. [55][56][57] Together, these results suggest that ancestry-related genetic factors may contribute to racial differences in tumor aggressiveness at diagnosis. 12 However, modifiable environmental pathways involving nSES, individual SES, behaviors, and clinical management may be more important drivers of survival disparities.…”

“…In the present study, Black women living in more advantaged neighborhoods experienced lower mortality in age-adjusted models. Associations between nSES and mortality attenuated following adjustment for potential mediators, including individual SES, behavioral factors, and comorbidities . Together, these results suggest that ancestry-related genetic factors may contribute to racial differences in tumor aggressiveness at diagnosis .…”

“…Among 1575 participants included in the study, median (IQR) African ancestry was 85% (76%-90%) and median (IQR) age was 55 (46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63) years. WCHFS participants in the highest compared with lowest quartile of African ancestry were more likely to have never smoked, have higher BMI, have a high school graduate education or lower, have less than $25 000 in household income, reside in the lowest quartile of nSES index, and to present with ER − tumors (Table 1 a Wilcoxon or Kruskal-Wallis nonparametric tests were used to compare medians across quartiles of African ancestry; χ 2 test of independence was used to compare prevalence.…”

Cancer Risk in a Large Inception Systemic Lupus Erythematosus Cohort: Effects of Demographic Characteristics, Smoking, and Medications

“…Previous assessment of cancer risk in SLE had also highlighted White race/ethnicity as a risk factor (10), which may reflect a decreased risk of certain cancer types (particularly breast) in women of non-White race/ethnicity (11). Among 824 White patients, 44 cancers occurred (5.3% [95% CI 4.0-7.1]); this proportion was numerically higher than the percentage in Black or Asian individuals, but the confidence intervals overlapped (6 cancers in 276 black patients, 2.2% [95% CI 1.0-4.7], versus 6 | 1793 cancers in 255 Asian patients, 2.4% [95% CI 1.1-5.0]).…”