Supplementary Material for: Liver resection in synchronous bilobar versus unilobar colorectal liver metastases: A retrospective analysis of oncological outcomes and patient survival

Background: Resection of colorectal liver metastasis has emerged as the standard treatment. Our study compares oncological outcomes of patients with resected synchronous bilobar versus unilobar colorectal liver metastasis. Methods: This retrospective study presents long-term follow-up data of 105 consecutive patients with primary colorectal cancer and synchronous liver metastasis. All patients underwent primary tumor and metastasis resections between 2007 and 2019. Results: 55 patients with bilobar and 50 patients with unilobar colorectal liver metastases were included. No significant difference in overall, tumor-specific or recurrence-free survival was observed between patients with bilobar and unilobar metastases. After case-control matching, the results were confirmed in patients with similar tumor burden. In the multivariate analysis, chemotherapy following liver metastasis resection was a significant prognostic factor associated with poor overall survival (HR 0.518, 95%CI 0.302-0.888, p=0.017). Conclusion: Overall survival, as well as tumor-specific and recurrence-free survival did not differ between patients with unilobar and bilobar liver metastasis. These findings add to the knowledge that primary tumor and metastasis resection in eligible patients improve the long-term outcome.