Patient selection and study design

All patients with SCLM were discussed by the multidisciplinary team. Treatment decisions were based on location and complexity of resection of the primary tumor, extent of liver resection, liver function and physical condition of the patients. The policy of the institution is not to combine a simultaneous major liver resection (≥ 3 segments) with complex colorectal procedure (e.g. total colectomy, low anterior resection). The most ideal candidates for combined laparoscopic liver resection were patients with solitary, peripherally located metastasis in anterolateral segments.

Study subjects were identified from a prospectively maintained database of patients who underwent liver resections for CLM from January 2000 to December 2016 at the Department of Abdominal and General Surgery, University Medical Centre Maribor. This institution is a tertiary referral center with more than 15 years’ experience in laparoscopic colorectal and with 8 years’ experience in laparoscopic liver surgery. SCLM were defined as those identified at the time of diagnosis of the primary colorectal cancer. All patients gave their informed consent. Ethical approval for this study was obtained from the local institutional review board. Patient records were anonymized and deidentified prior to analysis.

All patients in the database who submitted to simultaneous laparoscopic resection of both the primary tumor and SCLM were selected and included in the study. Those laparoscopic patients were compared to patients that underwent open simultaneous liver and colorectal resection for stage IV colorectal cancer. A propensity score matching was applied to identify the most comparable patients from the open surgery group. Primary endpoints of the study were perioperative and oncologic outcomes. Secondary endpoints of the study were overall survival (OS) and disease-free survival (DFS).