gms | German Medical Science

50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds)
12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie (dae)

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie
Deutsche Arbeitsgemeinschaft für Epidemiologie

12. bis 15.09.2005, Freiburg im Breisgau

Lifetime occupational and recreational physical activity and risks of colon and rectal cancer: a case-control study

Meeting Abstract

  • Karen Steindorf - Deutsches Krebsforschungszentrum (DKFZ), Heidelberg
  • Wieslaw Jedrychowski - University of Krakow, Krakow, Poland
  • Martina Schmidt - Deutsches Krebsforschungszentrum, Heidelberg
  • Tadeusz Popiela - University of Krakow, Krakow, Poland
  • Jürgen Wahrendorf - Deutsches Krebsforschungszentrum (DKFZ), Heidelberg

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie. Deutsche Arbeitsgemeinschaft für Epidemiologie. 50. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds), 12. Jahrestagung der Deutschen Arbeitsgemeinschaft für Epidemiologie. Freiburg im Breisgau, 12.-15.09.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05gmds103

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Veröffentlicht: 8. September 2005

© 2005 Steindorf et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction and Aims

In 2002, the International Agency for Research on Cancer [1] summarized that there is sufficient evidence in humans for a cancer-preventive effect of physical activity for colon cancer. Studies on rectal cancer yielded less consistent results. Nevertheless, important aspects of the associations between physical activity and colon and rectal cancer risks are still under discussion [2], especially the impact of physical activity at different ages and possible confounding and effect modifications by other lifestyle factors, especially diet. A second limitation of the current evidence is that many studies used a rather crude physical activity assessment. However, an adequate exposure assessment that will capture the different dimensions of activity is needed to elaborate on concrete public health recommendations. The life period at which physical activity may have its greatest impact, and whether a certain level of activity needs to be sustained throughout life was not considered in most of the studies either.

Material and Methods

In 2000-2003, 239 incident cases of colorectal cancer, 98 with colon and 141 with rectal cancer, confirmed by histopathology and 239 controls, matched by age and gender, were enrolled from the First Surgical Clinic of the University Hospital in Krakow [3]. Controls were chosen from among patients with no history of cancer from the same hospital and admitted for treatment for non-neoplastic conditions unrelated to digestive tract diseases. Data on occupational and recreational physical activity were collected in standardized personal interviews for the ages 20, 30, 40, 50, and 60 years. For recreational activity, participants reported on their activity in sports, household tasks, gardening, walking and cycling, separately for summer and winter times. The reported time spent for each activity per week was multiplied by its typical energy expenditure requirements expressed in metabolic equivalents (MET) [4], and added together to yield an MET-hours per week score. Total physical activity was estimates as the sum of all reported activities. Besides lifestyle and socio-demographic characteristics, such as education, occupation and lifetime smoking, the usual dietary pattern for 148 beverage and food items was assessed within an interviewer-administered food frequency questionnaire.

Beyond standard descriptive statistics, we used unconditional logistic regression models adjusted for age and gender to estimate odds ratios and the corresponding 95 percent confidence intervals. In addition to models with the basic adjustment, multiple regression analyses were applied to allow for further adjustment. As potential confounding variables we investigated body mass index, total energy intake, fiber intake, calcium intake, alcohol intake, and smoking habits (lifetime packyears).

Results

In multivariate logistic regression for colon cancer, all higher levels of total physical activity were associated with reduced odds ratios compared with the lowest quartile of physical activity in the multivariate adjusted model. The odds ratios for the highest quartile consistently yielded the smallest odds ratios compared to the other quartiles. Significant risk reductions for the highest quartile were found for total lifetime, age 30, 40 and 50, and for the time periods 10 years ago, 30 years ago, and 40 years ago. The highest risk reduction was found for persons whose total physical activity was classified in the highest quartile at age 50, resulting in an odds ratio of 0.21 (95 percent confidence interval (CI): 0.06, 0.77). For lifetime physical activity, the multivariate adjusted odds ratio for the highest activity group (≥ 200 MET-hours/week) was 0.37 (95 percent CI: 0.17, 0.83). Looking at behavioral patterns over lifetime, lifelong high-exercisers had a significantly reduced risk of 0.26 (95 percent CI: 0.08, 0.84) compared to lifelong non-exercisers. Lifelong medium-exercisers had a non-significantly reduced risk of 0.44. Total energy intake modified the effect of physical activity where the protective effect for colon cancer was more pronounced in persons with a high-energy intake. Looking at the different components of total physical activity, high levels of occupational physical activity dominated the risk reductions. We did not observe notable confounding or effect modification for other lifestyle factors. For rectal cancer, we did not find a consistent association or significant trends between total physical activity and rectal cancer for the different ages and lifetime periods.

Discussion

This study confirms and extends highly consistent prior observations that higher levels of physical activity remarkably decrease the risk of colon cancer but not rectal cancer. We could not identify a specific age at which high levels of physical activity are most protective against colon cancer. The highest risk reduction was found for those subjects who reported lifelong high levels of physical activity. Proposed biologic mechanisms include gastrointestinal transit time, prostaglandins and bile acids secretion, gastrointestinal-pancreatic hormone profiles, and immune function modulation. Serum cholesterol, insulin resistance, and insulin-like growth factors are also considered [5]. Physical activity is a modifiable lifestyle factor and, thus, has a high potential for cancer prevention. Controlled trials of exercise interventions are needed to develop cancer prevention programs addressed to the general population.


References

1.
Vainio H, Bianchini F. (eds): Weight Control and Physical Activity. Lyon: International Agency for Research on Cancer, 2002.
2.
Wei EK, Giovannucci E, Wu K, et al. Comparison of risk factors for colon and rectal cancer. Int J Cancer 2004; 108: 433-42.
3.
Steindorf K, Jedrychowski W, Schmidt M et al. Case-control study of lifetime occupational and recreational physical activity and risks of colon and rectal cancer. Eur J Cancer Prev 2005; in press.
4.
Ainsworth BE, Haskell WL, Whitt MC, et al. Compendium of physical activities: an update of activity codes and MET intensities. Med Sci Sports Exerc 2000; 32: S498-S504.
5.
Quadrilatero J, Hoffman-Goetz L. Physical activity and colon cancer. A systematic review of potential mechanisms. J Sports Med Phys Fitness 2003; 43: 121-38.