Effects of exercise by type and duration on quality of life in patients with digestive system cancers: A systematic review and network meta-analysis

Background: There is scant evidence regarding the effects of exercise type and duration on quality of life (QoL) in digestive system cancer (DSC) survivors. We aim to investigate the optimal type and duration of exercise to improve QoL for DSC survivors through a systematic review and network meta-analysis.Methods: A systematic literature search of PubMed, Embase, and Web of Science was performed. Eligibility for study inclusion was limited to studies that were randomized controlled trials involving all kinds of exercise in adult patients with DSCs, and the comparator was in standard care or other types of exercise. The primary outcome was QoL, including general health, physical health, mental health, and role function. Secondary outcomes included cancer-related symptoms such as fatigue, insomnia, depression, anxiety, and duration of hospital stay. The network meta-analyses were performed using a random-effect model.Results: The analysis included 32 eligible articles and a total of 2558 participants. Our primary outcome indicated that short-term aerobic exercise significantly enhanced general health (standardized mean difference (SMD) = 0.66, 95% credible intervals (CrIs): 0.05 to 1.30), and also contributed to a better mental health (SMD = 0.38, 95%CrI: -0.05 to 0.81) and role function (SMD = 0.48, 95%CrI: -0.27 to 1.20). Although without significant changes, short-term resistance exercise tended to increase the physical health of patients with DSCs (SMD = 0.69, 95%CrI: -0.07 to 1.50) and effective in alleviating fatigue (SMD = -0.77, 95%CrI: -1.50 to 0.01). Short-term aerobic exercise was related to a lower score of insomnia (SMD = -1.20, 95%CrI: -2.40 to 0.06), depression (SMD = -0.51, 95%CrI: -1.50 to 0.45), and anxiety (SMD = -0.45, 95%CrI: -1.30 to 0.34). All types of exercise related to a trend of declined hospital stays (-0.87 to -5.00 day). Long-term resistance exercise, however, was negatively associated with general health (SMD = -0.33, 95%CrI: -1.70 to 1.00), physical health (SMD = -0.18, 95%CrI: -1.30 to 0.90), and role function (SMD = -1.20, 95%CrI: -2.50 to 0.11).Conclusion: This study suggests that short-term aerobic exercise, with or without resistance exercise programs, enhances QoL (especially for general health) as well as relieves cancer-related symptoms for DSC survivors, while long-term resistance exercise may have negative effects, and thus should be adopted cautiously. These results provide important evidence for the management of DSCs.