Gesundheitswesen 2017; 79(08/09): 656-804
DOI: 10.1055/s-0037-1605862
Vorträge
Georg Thieme Verlag KG Stuttgart · New York

Mediating Factors of the Association between Physical Activity and Colon Cancer: Lessons from the EPIC Cohort

K Aleksandrova
1   DIfE-Potsdam-Rehbrücke, Ernährung, Immunität und Metabolismus Start-up Lab, Epidemiologie, Nuthetal
,
M Jenab
2   International Agency for Research on Cancer (IARC-WHO), Lyon
,
M Leitzmann
3   Department of Epidemiology and Preventive Medicine, Regensburg University Medical Center, Regensburg
,
B Bueno-de-Mesquita
4   National Institute for Public Health and the Environment, Bilthoven
,
R Kaaks
5   Division of Cancer Epidemiology, German Cancer Research Centre, Heidelberg
,
E Riboli
6   Division of Epidemiology, Public Health and Primary Care, Imperial College, London
,
H Boeing
7   DIFE-Potsdam-Rehbrücke, Epidemiologie, Nuthetal
› Author Affiliations
Further Information

Publication History

Publication Date:
01 September 2017 (online)

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Background:

Accumulating evidence has emerged suggesting an association between physical activity and lower risk of colon cancer; however, the underlying biological mechanisms remain largely unknown. We quantified potential mediation effect of body fatness and biomarkers of various biologically plausible pathways on the association between physical activity and colon cancer.

Methods:

We conducted a nested case-control study in a cohort of 519,978 men and women. A total of 713 incident colon cancer cases were matched using risk-set sampling to 713 controls on age, sex, study center, fasting status, and hormonal therapy use. The amount of total physical activity during the past year was expressed in metabolic equivalent of task [MET]-hours/week. Anthropometric measurements and blood samples were collected at study baseline. Mediation effects were estimated as proportion of explained effect (PEE) of individual biomarkers to the multivariable-adjusted model using the difference of coefficients method.

Results:

High physical activity was associated with a lower risk of colon cancer (Relative Risk ≥91 MET-hours/week versus < 91 MET-hours/week = 0.75 [95% Confidence Interval (CI): 0.57 to 0.96]. In mediation analyses, this association was accounted for by waist circumference [proportion explained effect (PEE)= 17%; CI: 4% to 52%] and the biomarkers soluble leptin receptor (sOB-R) [PEE = 15%; 95% CI: 1% to 50%] and 5-hydroxyvitamin D (25[OH]D) [PEE = 30%; 95% CI: 12% to 88%]. In combination, these factors explained 45% (95% CI: 20% to 125%) of the association. Beyond waist circumference, sOB-R and 25[OH]D additionally explained 10% (95% CI: 1%; 56%) and 23% (95% CI: 6%; 111%) of the association, respectively.

Conclusion:

The inverse association between physical activity and colon cancer risk could be partially explained by abdominal fatness and biomarkers of metabolic dysfunction, immunity and vitamin D metabolism.