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.
