Exploration of Lifestyle and Health Behaviors in Cancer Survivorship Populations

Abstract

BACKGROUND: Incident obesity-related cancers are on the rise, especially among younger adults and women. Obesogenic behaviors, including poor diet and low physical activity may contribute to carcinogenesis and comorbidities in survivorship including metabolic syndrome. Adolescent and young adult (AYA) cancer survivors have a longer survivorship duration and are at increased risk for adverse metabolic late-effects. Current existing guidelines to promote healthy lifestyle behaviors for cancer prevention, including those from the American Cancer Society (ACS), support a dietary pattern high in fruits and vegetables with adequate fiber, physical activity, and the limited use of dietary supplements. Such health behaviors in survivorship may be influenced by health beliefs. Evidence is limited in regards to interventions targeted to improve dietary behaviors among AYA cancer survivors, adherence to current recommendations among AYA cancer survivors and adult/older adult cancer survivors (AOA) and the role of health beliefs in achieving recommendations, and the role of fiber supplementation on colorectal cancer risk. OBECJTIVES: This dissertation is composed of three aims addressing health behaviors in cancer survivorship to: 1) synthesize the theoretical constructs and support components of dietary interventions targeting adult survivors of AYA cancer, 2) examine AYA and AOA cancer survivor health beliefs and adherence to ACS guidelines, and 3) evaluate the association between fiber supplement use and colorectal cancer risk and mortality in post-menopausal women. METHODS: A systematic review of current literature was conducted for Aim 1 to include interventions targeting dietary intake change towards recommendations among survivors of AYA cancer. Seven databases were searched and eligible studies were evaluated for quality and bias and narrative synthesis was used to identify themes. Cross sectional analysis of survey data in a nationally representative sample of adults participating in the Health Information National Trends Survey (HINTS) was completed for Aim 2 to compare behaviors between AYA and AOA cancer survivors, as well as evaluate the role of health beliefs in meeting recommendations in adult cancer survivors. Statistical models included logistic and linear regression models to assess meeting fruit and vegetable intake, and aerobic and resistance physical activity recommendations aligned with current ACS guidelines. For Aim 3, hazard regression models using data from the Women’s Health Initiative (WHI) were completed to evaluate association between fiber supplement use and colorectal cancer (CRC) risk and mortality. Sensitivity analyses were completed to evaluate presence or absence of metabolic syndrome on cancer outcomes. RESULTS: In the systematic review from Aim 1, four studies met eligibility criteria. Sample sizes were limited and the majority of studies included participants on the older age-range of AYA. The most prevalent theory was Social Cognitive Theory and three of the four interventions included a physical activity component. Important considerations when designing interventions for this population were identified as external factors, population heterogeneity, intervention components and feasibility/efficacy. Regarding Aim 2, AYA were half as likely to meet aerobic physical activity guidelines than AOA cancer survivors but there were no other statistically significant differences observed. The majority of adult cancer survivors did not meet individual recommendations. Health beliefs associated with meeting recommendations included self-efficacy, barriers-to-benefits ratio, and cue to action. Findings for Aim 3 indicate that fiber supplement use is not associated with CRC risk or mortality. The use of insoluble fiber prebiotics compared to no use was associated with higher CRC-mortality. There was no effect of presence of metabolic syndrome on observed cancer outcomes. CONCLUSION: Few dietary interventions are tailored for AYA and theory-based interventions including physical activity may be complementary to dietary change in this population of cancer survivors. Many adult cancer survivors in the US do not meet aerobic and resistance physical activity, fruit, and vegetable intake recommendations for cancer prevention. Health beliefs and behaviors overall are similar between AYA and AOA cancer survivors. Targeting self-efficacy and providing a cue to action may promote healthy lifestyle behaviors among cancer survivors. Fiber supplement use was not associated with CRC risk while insoluble fiber use was associated with higher CRC-mortality and is not recommended as CRC-risk reduction strategy. Collectively, the findings of this dissertation indicate the need to tailor interventions to promote current healthy lifestyle behavior recommendations in cancer survivorship populations.