The effects of physical activity, fast-mimicking diet and psychological interventions on cancer survival: A systematic review and meta-analysis of randomized controlled trials

Background: Health professionals are often asked if non-pharmacological interventions prolong life. This review aims to evaluate the effects of physical activity, fast-mimicking diet (FMD) and psychological interventions on survival in all cancers. Methods: A systematic review and meta-analysis of randomized controlled trials (RCTs). Only RCTs of physical activity, FMD and psychological interventions (including counselling, cognitive and other psychotherapies) in cancer patients that reported survival outcomes were included. Data sources: CENTRAL, MEDLINE, Embase, CINAHL, APA PsycINFO, Web of Science, ICTRP and ClinicalTrials. gov from inception to January 2020 were searched without language restrictions. The protocol was prospectively registered at PROSPERO (CRD42019160944). Results: Thirty-one RCTs (9 on physical activity and 22 on psychological interventions) were included in the final analysis after evaluation of 60,207 records from our initial search. No eligible RCT on FMD was reported. RCTs on group psychological interventions (41.9 %) and in patients with breast cancer (38.7 %) were the most common. Most evaluated short-term interventions and in primary or adjuvant settings. Only one of 9 (11 %) RCTs on physical activity and 8 of 22 (36 %) RCTs on psychological interventions were associated with improved overall survival. Only group psychological interventions in breast cancer had adequate number of RCTs to allow a meta-analysis to be performed. It demonstrated a trend towards improved overall survival (HR -0.20, 95 %CI -0.49 to 0.10), particularly in RCTs that evaluated long-term (>6 months) therapies (HR -0.29, 95 %CI -0.59 to 0.01). Conclusion: Longer term interventions starting early in the patients? care journey in primary and adjuvant settings have shown the most promise for improving survival. Better designed RCTs including survival outcomes are particularly needed in non-breast cancers.