PRelationship Between Physical Activity and Cancer Ris

Overview

This protocol is a sub-study of the ongoing "Protect Health and Reduce Cancer Risk" study conducted in Shanghai, China, and sponsored by the Shanghai Cancer Institute, Vanderbilt University, and the National Cancer Institute. The parent study is designed to examine the relationship of diet, lifestyle, occupational, and environmental risk factors, as well as genetic variation, to cancer incidence in a large cohort of men in women between 40 and 70 years of age. The current sub-study will assess the validity and reliability of a new physical activity questionnaire for use in the parent study and to evaluate whether different types of activity and the frequency, intensity, and duration of activity are associated with markers that have been linked to cancer risk, such as C-reactive protein, interleukin 6 and soluble tumor necrosis factor alpha. Participants in the current 12-month study are selected from among men and women participating in the "Protect Health and Reduce Cancer Risk" study. Participants keep a diary of their physical activity and complete two 30-minute interviews about their physical activity, one at the beginning and one at the end of the study period. Every 3 months for 7 consecutive days, they wear a pager-sized activity monitor on their waist that records their physical activity patterns during that period of time. They provide blood and urine samples four times during the study and, at the end of the study, undergo a health examination that includes an electrocardiogram, body composition measurement, and physical fitness test. The fitness test is a step-test consisting of 3-minute stages in which the subject successively increases the stepping speed until reaching 85 percent of his or her predicted maximal heart rate. Blood and urine samples are analyzed for levels of nutrients and certain proteins, and are stored for future studies related to nutrition and physical activity and possibly for genetic studies related to health, nutrition, exercise, or disease.

In the past decade, China has experienced fundamental decreases in the populations' physical activity levels, due to increasingly sedentary occupations and lifestyles. However, the transition to a Western lifestyle has not reached the entire Chinese population. The resulting wide range of between-person variation in physical activity provides an unparalleled opportunity for physical activity studies. Although physical activity measurement techniques have evolved considerably over the past years, the main obstacle in quantifying physical activity is the complexity of precisely measuring its individual components, particularly low to moderate-intensity activities. Recently, investigators at Vanderbilt University, the Shanghai Cancer Institute, and the DCEG initiated two prospective population-based cohort studies: the Shanghai Women's Cohort and the Shanghai Men's Cohort. The aim of these studies is to prospectively examine the relations of diet, lifestyle, occupational, and environmental risk factors, as well as genetic variation, to cancer incidence among 75,000 women and 73,000 men, aged 40 to 70 years old, and residing in Shanghai, China. We propose to conduct a study among 600 women and men participating in these two cohort studies. The specific objectives of the current study are to develop a comprehensive physical activity questionnaire and to assess the validity and reliability of this instrument in the Shanghai cohorts using objective measures of physical activity/physical fitness: activity monitors, and the Modified Canadian Aerobic Fitness Test. In addition, we intend to evaluate whether different types and parameters of physical activity are associated with circulating levels of specific inflammatory markers that have been linked to cancer risk. The specific markers are C-reactive protein (CRP), interleukin 6 (IL-6), and soluble tumor necrosis factor alpha (TNF-a). The impact of potentially confounding variables of the association between physical activity and inflammatory markers, such as recent exercise, use of anti-inflammatory drugs, and current or recent infections, will be carefully accounted for in the analysis.