Abstract
Surgical resection is the gold standard for treating synchronous colorectal liver metastases (CRLM). The resection of the primary tumor and metastatic lesions can follow different sequences: "simultaneous", "bowel-first", and "liver-first". Conservative approaches, such as parenchymal-sparing surgery and segmentectomy, may serve as alternatives to major hepatectomy. A comprehensive search of Medline, Epistemonikos, Scopus, and the Cochrane Library was conducted. Studies evaluating patients who underwent surgery for CRLM and reported survival results were included. Other secondary outcomes were analyzed, including disease-free survival, perioperative complications and mortality, and recurrence rates. Quality assessment was performed using the AMSTAR-2 method. No significant differences in overall survival, disease-free survival, and secondary outcomes were observed when comparing simultaneous to "bowel-first" resections, despite a higher rate of perioperative mortality in the former group. The 5-year OS was significantly higher for simultaneous resection compared to "liver-first" resection. No significant differences in OS and DFS were noted when comparing "liver-first" to "bowel-first" resection, or anatomic to non-anatomic resection. Our umbrella review validates simultaneous surgery as an effective oncological approach for treating SCRLM, though the increased risk of perioperative morbidity highlights the importance of selecting suitable patients. Non-anatomic resections might be favored to preserve liver function and enable future surgical interventions.