Patients with resectable liver metastases of colorectal origin will be assigned to laparoscopic liver resection or conventional open liver surgery.

Blood samples will be drawn preoperatively and 24 hours after resection. Determination of Interleukin-6 (IL-6) and IL-8 will be done to assess the stress response between open and laparoscopic liver resection (Elisa test).

The Messenger Ribonucleic Acid (mRNA) of inflammation related factors (cyclooxygenase-2 (COX-2) and Matrix metalloproteinase (MMP-9)), angiogenesis related factor (vascular endothelial growth factor (VEGF) and hypoxia induced factor-1 (HIF-1)) in tumor tissue and normal liver parenchyma will be detected by real-time real time-Polymerase Chain Reaction (RT-PCR).

According to the null hypothesis, no difference in the IL6 postoperative value, between the two groups would be expected. To calculate sample size, a IL6 postoperative value of 100±40 pg/mL in the laparoscopic group and 60±40 mL/m pg/mL in the open group was hypothesized. Considering a two-sided α=0.05 and β=0.1, the minimal sample size required to achieve statistical significance was 17 subjects in both groups in a 1:1 randomization. Laparoscopic group was increased by 20% of patients considering a conversion rate of 20% accordingly. Randomization will be performed using computer-generated random numbers the day before operation and stopped when 20 patients per group will be reached.

Inclusion Criteria:

1. 18-80 years old
2. Patients with colorectal liver metastases
3. Colorectal liver metastases ≤10 cm in size -

Exclusion Criteria:

1. Patients not fit for laparoscopic surgery due to comorbidities
2. Patients with tumors close or infiltrating the major vessels -