Physical activity, the direct and indirect effect of socioeconomic status on risk factors of colorectal cancer in Canada

• Main Author: Zhao, Jing
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2012
• Subjects: Newfoundland; Canada
• Online Access: https://research.library.mun.ca/2417/; https://research.library.mun.ca/2417/1/Zhao_Jing.pdf; https://research.library.mun.ca/2417/3/Zhao_Jing.pdf

The objective of this thesis was to examine the determinants of colorectal cancer(CRC) from two perspectives: 1) the associations between recreational physical activity and the risk of CRC; 2) the direct and indirect effect of socioeconomic status on the risk of CRC. -- Higher levels of physical activity have been consistently associated with lower risk of CRC in previous studies. Nevertheless, the specific mode, intensity, frequency, and duration of physical activity required for CRC prevention are not well known and remain controversial. The first objective of this study is to examine the associations of walking, non-walking exercise, and total recreational physical activity on colorectal cancer development. The study used the data collected from the existing population based case-control study of Ontario (ON) and Newfoundland and Labrador (NL), in which personal history, life style and dietary information were collected using the Personal History Questionnaire (PHQ), Food Frequency Questionnaire (FFQ) and Family History Questionnaire (FHQ). Multivariable logistic regression analysis was used to estimate odds ratios(OR) and 95% confidence interval (95%CI) after adjusting potential confounding covariates. Pooled analysis in both ON and NL was also conducted. Results from this study showed that the highest quintile of walking was associated with increased colorectal cancer risk for both males and females in both provinces (highest VS lowest: ON: OR=1.51, 95%CI=l.07-2.13; NL: OR=2.01,95%CI=1.25-3.22; pooled analysis: OR=1.70, 95%CI=1.09-2.66). However, this result could be biased because a higher proportion of cases responded to this item than controls. Non-walking exercise was insignificantly associated with a reduced risk of colorectal cancer for both sexes and provinces. These findings suggested that increasing amounts of neither walking nor non-walking exercise was associated with reducing the risk of colorectal cancer. More specified prospective studies on physical activity are needed to evaluate effective ...