4. Statistical analyses The EORTC QLQ-C30 symptom subscale and the EORTC QLQ-STO22 subscale scores are reported using a scale from 0 to 100. Statistical analyses of the QOL outcomes evaluated the differences between the LADG and the ODG groups with respect to the overall changes from the preoperative scores (baseline) to those obtained at follow-up. To adjust for possible baseline differences, we included the baseline values in the model. All comparisons between groups were based on 'intent-to-treat' analyses in which patients were analyzed according to their assigned treatment group. Categorical variables were compared using the χ2 test, and continuous variables were analyzed using the Student's t-test. Analysis of Covariance (ANCOVA) with repeated measures was used to compare the two groups of patients with respect to overall changes in their short term quality of life after the surgery. The SAS (SAS Institute Inc., Cary, NC, USA) program called 'PROC GLM' was used.