Charlotte Jl Molenaar, Stefan J van Rooijen, Hugo Jp Fokkenrood, Rudi Mh Roumen, Loes Janssen, Gerrit D Slooter

Surgery is the cornerstone in curative treatment of colorectal cancer. Unfortunately, surgery itself can adversely affect patient health. 'Enhanced Recovery After Surgery' programmes, which include multimodal interventions, have improved patient outcomes substantially. However, these are mainly applied peri- and postoperatively. Multimodal prehabilitation includes multiple preoperative interventions to prepare patients for surgery with the aim of increasing resilience, thereby improving postoperative outcomes. To determine the effects of multimodal prehabilitation programmes on functional capacity, postoperative complications, and quality of life in adult patients undergoing surgery for colorectal cancer. We searched CENTRAL, MEDLINE, Embase and PsycINFO in January 2021. We also searched trial registries up to March 2021. We included randomised controlled trials (RCTs) in adult patients with non-metastatic colorectal cancer, scheduled for surgery, comparing multimodal prehabilitation programmes (defined as comprising at least two preoperative interventions) with no prehabilitation. We focused on the following outcomes: functional capacity (i.e. 6-minute walk test, VO2peak, handgrip strength), postoperative outcomes (i.e. complications, mortality, length of hospital stay, emergency department visits, re-admissions), health-related quality of life, compliance, safety of prehabilitation, and return to normal activities. Two authors independently selected studies, extracted data, assessed risk of bias and used GRADE to assess the certainty of the evidence. Any disagreements were solved with discussion and consensus. We pooled data to perform meta-analyses, where possible. We included three RCTs that enrolled 250 participants with non-metastatic colorectal cancer, scheduled for elective (mainly laparoscopic) surgery. Included trials were conducted in tertiary care centres and recruited patients during periods ranging from 17 months to 45 months. A total of 130 participants enrolled in a preoperative four-week trimodal prehabilitation programme consisting of exercise, nutritional intervention, and anxiety reduction techniques. Outcomes of these participants were compared to those of 120 participants who started an identical but postoperative programme. Postoperatively, prehabilitation may improve functional capacity, determined with the 6-minute walk test at four and eight weeks (mean difference (MD) 26.02, 95% confidence interval (CI) -13.81 to 65.85; 2 studies; n = 131; and MD 26.58, 95% CI -8.88 to 62.04; 2 studies; n = 140); however, the certainty of evidence is low and very low, respectively, due to serious risk of bias, imprecision, and inconsistency. After prehabilitation, the functional capacity before surgery improved, with a clinically relevant mean difference of 24.91 metres (95% CI 11.24 to 38.57; 3 studies; n = 225). The certainty of evidence was moderate due to downgrading for serious risk of bias. The effects of prehabilitation on the number of complications (RR 0.95, 95% CI 0.70 to 1.29; 3 studies; n = 250), emergency department visits (RR 0.72, 95% CI 0.39 to 1.32; 3 studies; n = 250) and re-admissions (RR 1.20, 95% CI 0.54 to 2.65; 3 studies; n = 250) were small or even trivial. The certainty of evidence was low due to downgrading for serious risk of bias and imprecision. The effects on VO2peak, handgrip strength, length of hospital stay, mortality rate, health-related quality of life, return to normal activities, safety of the programme, and compliance rate could not be analysed quantitatively due to missing or insufficient data. The included studies did not report a difference between groups for health-related quality of life and length of hospital stay. Data on remaining outcomes were not reported or were reported inadequately in the included studies. Prehabilitation may result in an improved functional capacity, determined with the 6-minute walk test both preoperatively and postoperatively. A solid effect on the number of omplications, postoperative emergency department visits and re-admissions could not be established. The certainty of evidence ranges from moderate to very low, due to downgrading for serious risk of bias, imprecision and inconsistency. In addition, only three heterogeneous studies were included in this review. Therefore, the findings of this review should be interpreted with caution. Numerous relevant RCTs are ongoing and will be included in a future update of this review.