Relationship between Change in Sitting Time and Risk of Cancer Incidence: A Prospective Cohort Study

Purpose: Cancer remains a leading global cause of morbidity and mortality; few studies have explored the impact of long-term changes in sitting time (ST) or its associations with cancer incidence risk across levels of insulin resistance.The aim of this study is to examine the association between daily ST, changes in ST over 2 years, and cancer risk.Methods: We analyzed data from 2,474 older adults participating in a Korean community-based cohort study.Daily ST and 2-year changes in ST were assessed using validated self-report questionnaires.Daily ST was categorized as 5 hours, 5 and 10 hours, and 10 hours per day.Two-year changes in ST were classified into four groups: consistently low (consistently inactive), decreased (formerly active), increased (newly active), and consistently high (consistently active).Cancer was classified according to the survey question.Multivariable extended Cox regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for cancer incidence.Results: Daily ST of 10 hours was associated with an 85% increased risk of cancer, even after adjusting for other confounding variables (HR, 1.84; 95% CI, 1.18-2.85).Also, after adjusting for confounding variables, the consistently ST group showed a 55% higher cancer risk (HR, 1.55; 95% CI, 1.02-2.36).These findings underscore the independent and interactive contributions of daily ST, changes in ST, and insulin resistance to cancer risk. Conclusion:This study demonstrates that daily ST of 10 hours or more or sustained high levels of ST over 2 years are associated with an elevated risk of cancer