**Background:** Cancer remains a major global health crisis, with 19 million new cases projected in 2022. Prehabilitation is a relatively new approach aimed at preparing patients for the stresses of treatment by optimizing physical and psychological status before surgery or therapy begins. Interventions can be exercise-based, nutritional, or psychological, and may be unimodal or multimodal. While previous reviews have focused on specific cancer subtypes or older/younger age groups, this review specifically addresses the young to midlife adult age range (18–55 years), a period where cancer prevalence increases for many types. The review also builds on existing literature by focusing on both functional outcomes (e.g., functional capacity, daily activity) and affective outcomes (anxiety, depression, stress, health-related quality of life).
**Methods:** A systematic review was conducted between January 2021 and October 2021, searching five databases: PsychINFO, CINAHL, MEDLINE, EMBASE, and PubMed. Search terms covered cancer, prehabilitation, intervention, and lifestyle concepts. Inclusion criteria required: any cancer type or stage, mean participant age between 18 and 55 years, peer-reviewed articles, prehabilitation interventions beginning before treatment, and inclusion of affective and/or functional outcome measures. Exclusion criteria included wrong disease type, child/adolescent/geriatric focus, study protocols or review articles, and non-English publications. A two-stage screening process with a secondary reviewer was employed using Covidence. Quality assessment used a 12-item checklist scoring 0–2 per item (total range 0–24), with scores of 17–24 representing good quality, 9–16 acceptable, and 0–8 low quality. Due to heterogeneity of outcome measures, a narrative synthesis approach was used.
**Key Results:** Of 6,324 studies initially screened, 4,631 remained after duplicate removal, 187 proceeded to full-text screening, and 13 were included. Eight studies were RCTs, with publication years ranging from 1999 to 2021. All studies used unimodal interventions. Eight employed psychological interventions (counselling, psychoeducation, mindfulness, psychosocial return-to-work support), four employed exercise interventions (aerobic, resistance, yoga), and only one employed a nutrition-based intervention (probiotic kefir). The mean participant age was 53 years, with 797 total participants. Participants were largely female (71% average); eight studies had 100% female samples. Breast cancer was the predominant cancer type (n=8 studies).
FOR AFFECTIVE OUTCOMES
Psychological interventions were moderately successful for anxiety, with four of seven interventions showing significant improvements. Effect sizes ranged from d=0.26 to d=0.59. Foley et al. reported large effects of mindfulness-based intervention from baseline to 3-month follow-up (p<0.002, d=0.59). Ambler et al. reported significant anxiety reduction pre-treatment to 2-week follow-up (p<0.003, d=0.45). For depression, three of five studies found significant moderate-to-large effects (d=0.33–0.83). Foley et al. reported clinically significant decreases (p<0.001, d=0.83). Health-related quality of life was assessed across all three prehabilitation modes, but results did not support statistically significant increases; only Li et al. reported significant pre-post effects on global health (d=1.3), mental health (d=0.53), and social function (d=0.31). Stress and distress were assessed in four studies, with only Foley et al. finding significant reduction (p<0.001, d=0.53).
FOR FUNCTIONAL OUTCOMES
Exercise prehabilitation showed moderate-to-large effects on functional capacity. The 6-minute walk backward test showed statistically significant improvements (d baseline-pre=0.55, p<0.035). The 400 m walk test was statistically significant (d baseline-pre=0.68). One study reported a 37 m improvement over the clinically significant distance on the 6-minute walk test. Case study data indicated over 40% improvement in 12-minute walk distance from baseline to post-intervention. Other measures (stair climbs, chair raises, arm curls) showed non-significant but moderate effects (d=0.39–0.68) and case study improvements of 5%–41%. The DASH measure showed a clinically meaningful increase of over 15 points pre-post-operatively.
QUALITY ASSESSMENT
All included studies were of acceptable or good quality. No evidence of reporting bias was found. Risk of selection bias was low for RCTs, though some studies lacked control groups or adequately outlined recruitment strategies.
**Clinical Implications:** The review provides moderate support for the clinical efficacy of exercise prehabilitation for improving functional capacity, with several studies reporting large improvements despite lacking statistical power. For anxiety, clinical improvements were observed even when statistical significance was not reached. The use of clinical change metrics allows for a more patient-centred approach. However, the large heterogeneity across all prehabilitation types and outcome measures prevented meta-analysis and limits generalisability. The over-representation of female participants and breast cancer, while reflective of population incidence rates for this age group, may confound findings. The review highlights the need for standardised functional and affective assessment batteries, increased focus on young to midlife adults across cancer types, and incorporation of feasibility measures into all prehabilitation interventions to understand patient burden and improve adherence.