Influence of Anaesthetic Technique on Postoperative Cancer Outcomes in Adult Patients Undergoing Solid Tumour Surgery: A Systematic Review of Observational Evidence with an Updated Synthesis of Randomised Trials

Abstract

Background: Perioperative anaesthetic technique has been proposed as a modifiable determinant of long-term cancer outcomes because propofol and volatile anaesthetics have different immunological and tumour-biological effects. Earlier clinical evidence was dominated by retrospective cohorts and generated inconsistent associations. Methods: The original systematic evidence set was identified through Ovid MEDLINE and comprised 1,068 records, of which 1,060 were screened and 13 comparative retrospective cohorts were included after full-text assessment. A supplementary PubMed/MEDLINE and citation update was performed on 18 August 2026 to integrate current randomised evidence. Observational studies were appraised with ROBINS-I and synthesised without meta-analysis in accordance with SWiM principles; effect size, precision, sample size, design and risk of bias were considered in interpretation. Randomised evidence was cross-checked against the contemporary 11-trial meta-analysis by Mustafa et al. (2026), which used RoB 2 and GRADE. Results: All 13 observational cohorts were judged to be at serious overall risk of bias, mainly because anaesthetic exposure was not randomised and residual confounding could not be excluded. Several single-centre cohorts reported associations favouring propofol-based total intravenous anaesthesia (TIVA), whereas large digestive-cancer data and studies in breast, lung and oral cancer were null. Current randomised evidence does not corroborate a clinically meaningful survival advantage. The 2026 meta-analysis of 11 randomised trials (7,811 participants) found no significant difference in overall survival (hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.94-1.17), recurrence-free survival (HR 1.06, 95% CI 0.95-1.19), overall mortality (risk ratio 1.03, 95% CI 0.94-1.13) or cancer recurrence (risk ratio 0.92, 95% CI 0.76-1.12), with high certainty for the principal outcomes. Conclusions: Observational associations suggesting benefit from propofol-based TIVA are not supported by the stronger randomised evidence available to date. Anaesthetic maintenance technique should therefore not be selected solely with the expectation of improving cancer recurrence or survival. Tumour-specific mechanistic questions and residual uncertainty around recurrence remain appropriate targets for future research.