Although Colorectal Cancer (CRC) is the 2nd leading cause of cancer mortality, it is estimated that as many as 90% of CRC cases could be prevented through screening and healthy lifestyle, such as engaging in regular physical activity. Obese women, who are at higher risk for CRC, may be less likely to engage in cancer prevention behaviors than normal weight women. The purpose of this research project was to understand how obesity affects CRC screening and physical activity behavior in order to design appropriate intervention messages for decreasing CRC risk among obese women. The dissertation followed three aims. For Aim 1, national data on CRC screening were analyzed to better understand the combined influence of gender, weight and race on CRC screening practices. We found that obese white women were 34% less likely to have had a colonoscopy in the past 10 years (p=0.001), but that there was no significant relationship between screening and weight in African American women. For Aim 2, focus groups were conducted with unscreened obese women to better understand how weight affects compliance with screening and physical activity guidelines. We found that knowledge of CRC prevention was low among obese women. While many of the barriers cited were similar to those found with non-obese women, obese women had more co-morbidities which they may prioritize over cancer screenings tests. Women also cited many weight-related barriers to physical activity. Aim III consisted of an online evaluation of weight-targeted CRC prevention messages. White women were stratified by weight (obese vs. non-obese) and randomized to receive either 10 weight-targeted messages developed based on focus group findings or 10 generic messages about CRC screening and physical activity. Women rated messages using the Elaboration Likelihood (ELM) Scale; there were no differences between ELM scores of women who read weight-targeted vs. generic messages, but obese women in both conditions reported higher elaboration (p=0.02) and felt that the messages were more personally relevant (p=0.005) and believable (p=0.047) than non-obese women did. Together, data from these three aims can be used to inform the development of future CRC prevention interventions targeted at obese women
