Intermediate Biomarkers of Cancer Risk are Altered by DifferentIntensity Levels of Physical Activity in Older AdultsMalin

Sammanfattning: AbstractIntroduction: Cancer is the leading cause of death worldwide, and the risk increases as ageincreases. Additionally, chronic inflammation is highly prevalent in older adults, and isassociated with cancer. In this respect, physical activity (PA) seems to act as a preventive toolof both cancer, and chronic inflammation, by exerting anti-inflammatory properties. However,current knowledge on links between physical activity and inflammatory biomarkers in olderadults remains limited. Therefore, the present study aims to investigate the associationbetween objectively assessed time in different physical activity intensities and pro-, and antiinflammatoryintermediated biomarkers of cancer risk in older European adults. Material and Methods: Men and women older adults (aged 65-79 years; N = 888) wererecruited from four European centers. Accelerometer-based assessment of daily time spentsedentary (SED), in light (LPA), and in moderate-to-vigorous (MVPA) PA was conducted.The inflammatory markers C-reactive protein (CRP), tumor necrosis factor-α, interleukin-6,tumor growth factor-β1, leptin, interleukin-10 and adiponectin were assessed in bloodsamples using enzyme-linked immunosorbent assay (ELISA), and standardized procedureswere used to define indicators of the metabolic syndrome. Linear regression analysis based onisotemporal substitution modelling with 30-minutes periods of different physical activityintensities was used and the analysis was stratified by biological sex. Results: Replacing 30 minutes of either SED or LPA with a corresponding time in MVPAwas associated to reduced CRP levels in older men and women (P < 0.05). In older women,reduced leptin levels were associated with reallocation of time spent in SED with both LPAand MVPA, and with reallocation of time spent in LPA with MVPA (P < 0.05). In older men,replacing time in SED with either LPA or MVPA (P < 0.01) resulted in significantly reducedleptin levels. Finally, reallocation of 30 minutes in either SED or LPA with MVPA wasassociated with elevated adiponectin levels in older women only (P < 0.05). Conclusion: This study suggests that different important cancer-related biomarkers of chronicinflammation in older adults are affected by different intensity thresholds of physical activityand that the impact of physical activity is independent of several important confoundingfactors, including smoking, disease risk and medication.Key words: Inflammatory markers; systemic inflammation; chronic inflammation; exercise;training