Effect of unplanned conversion to open surgery on resection margins and postoperative complications in minimally-invasive resection of colorectal liver metastases: A systematic review and meta-analysis with meta-regression.

BACKGROUNDS/AIMS: To evaluate the impact of unplanned conversion to open surgery on resection margin status and postoperative complications in patients undergoing minimally-invasive resection of colorectal liver metastases (CRLM). METHODS: This study performed a proportion meta-analysis and meta-regression using random-effects modelling in accordance with PRISMA guidelines. Studies with at least 15 patients that reported conversion to open surgery in individuals receiving minimally-invasive CRLM resection were included. The association of unplanned conversion with postoperative outcomes was analyzed. RESULTS: Eighty-six studies encompassing 18,138 patients were analyzed. The overall conversion rate was 5.8% (95% CI 5%-6.6%). Conversion was associated with improved R0 resection rates (coefficient: 2.167, p < 0.001) but was also linked to increased postoperative mortality (coefficient: 7.585, p = 0.001) and morbidity (coefficient: 1.737, p = 0.003); there was no significant impact on 5-year overall survival (coefficient: 0.700, p = 0.989) or 5-year disease-free survival (coefficient: -72.900, p = 0.157). Specifically, conversion due to oncological concern was associated with higher rates of R0 resection (coefficient: 0.638, p = 0.005); conversion resulting from iatrogenic injuries was associated with lower R0 resection rates (coefficient: -1.478, p < 0.001); conversion for technical difficulties was associated with lower postoperative morbidity (coefficient: -0.380, p = 0.006). CONCLUSIONS: Unplanned conversion to open may carry prognostic and oncological implications for minimally-invasive resection of CRLM. Although conversion due to bleeding and iatrogenic injury is routinely considered, conversion prompted by technical difficulties or oncological concerns should not be considered failure, as it may be associated with improved patient outcomes.