Medical Research: Emerging Concepts and Applications Vol. 2

Gastrointestinal malignancies are concentrated in later life, and resection remains the principal curative modality for most of them. Chronological age has proved an unreliable guide to who tolerates such surgery well, and frailty has consequently been adopted across gastrointestinal surgical oncology as a marker of diminished physiological reserve. Adoption has outpaced conceptual and methodological consolidation. This critical narrative review examines how frailty is defined, measured and interpreted in patients undergoing resection for colorectal, gastro-oesophageal and hepatopancreatobiliary cancer, and evaluates the strength of the evidence linking it to short-term morbidity, survival, functional recovery and patient-valued outcomes. Literature was identified through Europe PMC and Crossref Metadata Search together with citation tracking and targeted searching of publisher and registry records, with a final search date of 5 June 2026. Two observations dominate the synthesis. First, the term frailty designates several non-equivalent constructs in this literature, ranging from a physical phenotype to comorbidity-weighted administrative indices, and prevalence, effect size and even the direction of some comparative conclusions depend on which construct is operationalised. Second, the association between frailty and adverse postoperative outcomes is reproducible across tumour sites and data sources, but the evidence supporting a causal and modifiable role remains substantially weaker, and is complicated by the difficulty of separating ageing-driven vulnerability from tumour-driven catabolism in patients whose disease itself impairs nutrition. Randomised evidence for multimodal prehabilitation in colorectal cancer is encouraging but limited in generalisability to the frailest patients, and comparable evidence for gastro-oesophageal and pancreatic resection is scarce. Reports that mild to moderate frailty may not compromise long-term quality of life after colonic resection sit uneasily alongside the prevailing risk-centred narrative and deserve fuller examination. Priorities include construct-explicit reporting, prospective head-to-head instrument comparison in surgical cohorts, trials powered in genuinely frail patients, adoption of function-anchored endpoints, and evidence generation outside the small number of high-income health systems that presently dominate the field.