Intermediate Biomarkers of Cancer Risk are Altered by Different Intensity Levels of Physical Activity in Older Adults

Abstract: Introduction: Cancer is the leading cause of death worldwide, and the risk increases as age increases. Additionally, chronic inflammation is highly prevalent in older adults, and is associated with cancer. In this respect, physical activity (PA) seems to act as a preventive tool of both cancer, and chronic inflammation, by exerting anti-inflammatory properties. However, current knowledge on links between physical activity and inflammatory biomarkers in older adults remains limited. Therefore, the present study aims to investigate the association between objectively assessed time in different physical activity intensities and pro-, and anti-inflammatory intermediated biomarkers of cancer risk in older European adults. Material and Methods: Men and women older adults (aged 65-79 years; N = 888) were recruited from four European centers. Accelerometer-based assessment of daily time spent sedentary (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 blood samples using enzyme-linked immunosorbent assay (ELISA), and standardized procedures were used to define indicators of the metabolic syndrome. Linear regression analysis based on isotemporal substitution modelling with 30-minutes periods of different physical activity intensities was used and the analysis was stratified by biological sex. Results: Replacing 30 minutes of either SED or LPA with a corresponding time in MVPA was 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 LPA and 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 reduced leptin levels. Finally, reallocation of 30 minutes in either SED or LPA with MVPA was associated with elevated adiponectin levels in older women only (P < 0.05). Conclusion: This study suggests that different important cancer-related biomarkers of chronic inflammation in older adults are affected by different intensity thresholds of physical activity and that the impact of physical activity is independent of several important confounding factors, including smoking, disease risk and medication.