The role of physical activity, sedentary behaviour, diet, adiposity and body composition on health-related quality of life and cancer-related fatigue after diagnosis of colorectal cancer: a Global Cancer Update Programme (CUP Global) systematic literature review and meta-analysis

Background: The impact of physical activity, sedentary behaviour, diet, adiposity, and body composition on health-related quality of life (HRQoL) and cancer-related fatigue among colorectal cancer survivors remains uncertain. Methods: PubMed, Embase, and CENTRAL were systematically searched until April 2023 for relevant randomised controlled trials (RCTs) and cohort studies. Random-effects meta-analyses or descriptive syntheses were conducted depending on the number of studies. The evidence was interpreted and graded by an independent World Cancer Research Fund Expert Committee and Expert Panel. Results: We included 31 RCTs (18 exercise, 14 diet) and 30 cohort studies (8 physical activity, 3 sedentary behaviour, 13 diet, 9 adiposity and body composition). Meta-analyses were possible for exercise RCTs that showed non-significant effects but indicative of improved HRQoL (overall four trials for global HRQoL, physical and emotional well-being) and fatigue (five trials). These studies were rated at a high risk of bias (RoB), and evidence was graded as ‘very low certainty of an effect’. Descriptive synthesis of interventions to improve diet quality suggested small improvements in global HRQoL and physical well-being, but with a high RoB rating leading to a ‘low certainty’ grading. Evidence from RCTs on probiotics and supplements and evidence from observational studies on sedentary behaviour, and various dietary and body composition factors was generally inconsistent and too scarce to draw conclusions. Conclusions: Exercise and diet quality interventions might improve HRQoL and fatigue outcomes in colorectal cancer survivors. The evidence overall was limited and should be strengthened by larger, well-designed RCTs across the cancer continuum.