Colorectal cancer is a leading malignancy, with synchronous colorectal liver metastases (CRLM) presenting in 20 % of patients. Resection remains the gold standard treatment for CRLMs, significantly improving survival outcomes. However, the optimal timing of resection of these synchronous lesions - simultaneous versus staged - remains controversial. This systematic review and meta-analysis synthesises data exclusively from propensity-score-matched and prospective studies. A comprehensive search of five databases identified 11 eligible studies, encompassing 2884 patients. Of these, 1453 underwent simultaneous resection, and 1431 underwent staged procedures. The primary outcome was 5-year overall survival (OS), with secondary outcomes including disease-free survival (DFS), surgical morbidity, operating time, and length of hospital stay. Meta-analysis demonstrated no significant difference in 5-year OS between simultaneous and staged resection groups (odds ratio [OR] 1.10, 95 % CI 0.75-1.61; p = 0.83). However, simultaneous resection was associated with significantly higher 3-year DFS (OR 1.67, 95 % CI 1.28-2.17; p = 0.0001) but also increased major surgical complications (Clavien-Dindo ≥ III: OR 1.32, 95 % CI 1.03-1.68; p = 0.03). This review highlights a lack of oncological advantage for simultaneous resection, coupled with higher morbidity, suggesting its use should be limited to select patients with low surgical risk. The findings underscore the need for well-powered, randomised trials to confirm these conclusions, as well as assess quality of life and economic outcomes, however delivering such trials in this patient cohort brings unique challenges. Until such data are available, clinical decision-making should remain individualised, guided by multidisciplinary discussion and available local expertise.

1st Faculty of Medicine Charles University Prague Czech Republic

Bodleian Healthcare Libraries University of Oxford United Kingdom

Faculty of Medicine Al Quds University Al Azhar Branch Gaza Palestine

Nuffield Department of Surgical Sciences University of Oxford Oxford United Kingdom; Oxford Hepatobiliary and Pancreatic Surgery Unit Oxford University Hospitals NHS Foundation Trust Oxford United Kingdom

Oxford Hepatobiliary and Pancreatic Surgery Unit Oxford University Hospitals NHS Foundation Trust Oxford United Kingdom

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