Slattery, Potter, Caan, Edwards, Coates, Ma, and Berry (1997) researched energy balance and colon cancer. The authors indicated why the study was undertaken; the abstract was informative. Past studies correlate low levels of physical activity and high levels of energy intake and body mass with colon cancer; this study investigated how the physical inactivity interacts with energy balance components (energy intake and body mass) to determine this risk.
The introduction provides background information related to the study. The incidence of colon cancer is high in Westernized countries making it an important area of study. The Western lifestyle includes physical inactivity with high energy consumption, increased body weight, and high rates of colon cancer. Case-control and cohort studies and studies of leisure activity show physical activity to be linked with lower risk of colon cancer. Energy intake and body size are only linked with colon cancer in some studies. There is limited data evaluating the combined associations of physical activity, energy intake, and body size with colon cancer; the combined effects of all three factors in the energy balance equation remains unknown.
Although the background information offered was adequate, additional information regarding relevant past studies would have provided a further understanding of the current study. For example, statements regarding physical activity and energy intake are vague and lack operational definitions which results in a lack of clarity regarding these factors and their association with cancer. It is also not clear at this point what the authors are referring to regarding "energy balance equation" (p. 75).
Data was gathered from 2073 first primary cases of colon cancer and 2466 age- and sex-matched controls (between 30 and 79 years). Physical activity was assessed by intensity of activities performed at home, leisure
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