Associations Between Adherence to Lifestyle Behaviors and Obesity-Related Cancer Risk and Outcomes Among Black/African American and Hispanic/Latino Adults

Date of Award

Spring 2022

Document Type


Degree Name

Doctor of Philosophy (PhD)


Public Health

First Advisor

Irwin, Melinda


BackgroundObesity is a chronic disease that has been established in the etiology of at least 14 cancers. Rates of many of these obesity-related cancers (ORC) have been increasing among Black/African American and Hispanic/Latino populations. Following the American Cancer Association’s (ACS) nutrition and physical activity cancer prevention guidelines has been associated with a 10-61% reduction in overall cancer incidence and mortality. However, just 5 to 14% of the general population and cancer survivors follow these guidelines. Limited research suggests that adherence with the cancer prevention guidelines results in a greater reduction in cancer risk and mortality for Black/African American and Hispanic/Latino adults relative to Non-Hispanic White populations. Significant structural and contextual (e.g., neighborhood environment, access to and transfer of knowledge) barriers remain that prevent communities of color from adopting and maintaining long-term adherence to these healthy behaviors. Most research on these associations does not account for the neighborhood context in which people live, which is hypothesized as a risk factor for adverse lifestyle behaviors and cancer risk and outcomes. Lastly, prior research has been limited by potential overestimation of the magnitude of effect of guideline adherence on cancer given inadequate interpretations of traditional statistical models and lack of accounting for competing events. MethodsIn three separate papers, we examined levels of adherence to the nutrition and physical activity cancer prevention guidelines among Black/African American and Hispanic/Latino adults with and without a history of cancer; the structural determinants of guideline adherence among cancer survivors; the associations between guideline adherence and ORC risk and outcomes; and the role of neighborhood context on this association. For the first study (Chapter 2), using a competing risk framework, we examined whether adherence to the lifestyle guidelines was associated with incidence of ORCs and whether this association was moderated by neighborhood socioeconomic status among 9,204 Hispanic/Latino adults enrolled in the NIH-AARP Diet and Health Study. For the second study (Chapter 3), using a multistate framework with competing risks, we examined the association between guideline adherence and risk and mortality from ORC as well as a subset of less common ORCs, and whether these associations were moderated by neighborhood socioeconomic status among 9,297 Black/African American and 4,215 Hispanic/Latino post-menopausal women enrolled in the Women’s Health Initiative Study. In the last study (Chapter 4), we used data from semi-structured interviews with 16 Black/African American and 10 Hispanic/Latino female breast cancer survivors and 10 oncology healthcare providers to identify the structural determinants of adoption and long-term adherence to the nutrition and physical activity recommendations. ResultsIn Chapter 2, we found an unadjusted cumulative risk of obesity-related cancers over a 15-year period that was not significantly different between ACS guideline adherence categories (high cumulative incidence function (CIF): 2.2% - 5.8%; moderate CIF: 2.2% - 6.6%; low CIF: 2.3% - 6.7%, PGray’s log rank = 0.690). In adjusted Fine and Gray models with competing events, high adherence to the ACS lifestyle guidelines was associated with a reduced probability of developing an ORC (SHR: 0.76, 95% CI: 0.58 – 1.00) compared to low adherence (Ptrend = 0.039), although it did not reach statistical significance. Due to reduced statistical power, we were unable to find effect modification by neighborhood socioeconomic status in this association. In Chapter 3, among Black/African American women, ACS guideline adherence was associated with lower ORC incidence (CSHR high vs. low: 0.68, 95% CI: 0.54-0.86), but not all-cause mortality (HR high vs. low: 0.83, 95% CI: 0.54-1.27). Among Hispanic/Latino women, there were similar patterns for guideline adherence with ORC incidence (CSHR high vs. low: 0.58, 95% CI: 0.36-0.93) and all-cause mortality (HR high vs. low: 0.81, 95% CI: 0.32-2.06). Associations with less common ORCs were mixed, with protective effects for incident less common ORC (Ptrend = 0.002) and increased risk of all-cause mortality after less common ORC (Ptrend = 0.000). No associations were found between guideline adherence, ORC-specific deaths, and effect modifier. In Chapter 4, Survivors identified substantial confusion on the evidence regarding lifestyle behaviors and breast cancer, stemming from inadequate healthcare provider counseling and an overreliance on informal sources of information. Providers identified lack of evidence-based knowledge as a barrier to counseling on these topics. There was a mixed perspective regarding the consistency of evidence, stemming from accessing evidence-based knowledge from a wide range of professional resources. Therefore, many healthcare providers in oncology care relied on generic messaging on lifestyle behaviors after a cancer diagnosis. ConclusionAcross our studies, we found low levels of high guideline adherence among Black/African American and Hispanic/Latino adults with and without a history of cancer. Structural determinants identified in qualitative interviews by breast cancer survivor and oncology healthcare providers explained the reasons for the low levels of guideline adherence. Our quantitative studies provided supporting evidence for an association between adherence to ACS nutrition and physical cancer prevention guidelines and a reduction in incidence of ORCs, including less common ORC, among Black/African American and Hispanic/Latino adults. Despite some of our findings not reaching statistical significance, the large magnitude of the associations in the presence of competing events across all outcomes indicates these lifestyle behaviors may be critically important for cancer risk and mortality in Black/African American and Hispanic/Latino populations. While our findings for residential poverty did not show a modifying effect, likely because of lack of power, we believe that context is critical for studying lifestyle behaviors and cancer disparities going forward. Additionally, public health interventions that address barriers to knowledge transfer from academia to providers to patients and communities at large and generate a consistent, uniform public message on lifestyle behaviors for cancer prevention are critical to address low levels of healthy behaviors among communities of color.

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