Evaluation of the Learning Curve of Total Mesorectal Excision for Rectal Cancer: Comparison of the Laparoscopic and Robotic Approaches

Hyejin Kim, MD, Gyu-seog Choi, MD, PhD, Junseok Park, MD, PhD, Sooyeun Park, MD. Colorectal Cancer Center, Kyungpook National University Medical Center, School of Medicine, Kyungpook National University.

INTRODUCTION: The technical difficulties experienced during laparoscopic total mesorectal excision (LTME) have prompted many surgeons to adopt the robotic approach. However, the comparison of learning process with robotic total mesorectal excision (RTME) in treating rectal cancer has not yet been clearly described. We compared the learning curves of LTME and RTME in different learning periods. We also compared the clinical outcomes of the 2 different approaches performed by the same surgeon during the same period for a detailed assessment of safety of RTME.

METHODS AND PROCEDURE: We reviewed records on the first 167 patients who underwent LTME from December 2002 to April 2005 (early LTME group) and compared them with data on the first 167 patients who underwent RTME from December 2007 to August 2012 in order to compare the each learning curve. To compare the clinical outcomes of these 2 approaches, data on 167 patients who underwent LTME from December 2007 to November 2009 (late LTME group) were compared with data on those who underwent RTME during the same period.

RESULTS: The learning curves of the surgical approaches were evaluated on the basis of risk-adjusted CUSUM analysis based on conversion, operative time, perioperative morbidity and circumferential resection margin status. The results showed that the learning curve plateaued after 65 cases for early LTME as opposed to after 32 cases for RTME. During the learning period, total operative time was significantly shorter in the RTME group than in the early LTME group (252.0 ± 42.1 min vs. 278.6 ± 49.2 min, P = 0.010). The mean length of the distal resection margin was significantly longer and the number of retrieved lymph nodes was significantly greater in the RTME group than in the early LTME group. In the same period, total operative time was significantly longer in the RTME group than that in the late LTME group (212.0 ± 49.8 vs. 156.4 ± 40.3, P < 0.001). Although patients with low rectal cancer who underwent preoperative chemoradiation, were higher comprised in the RTME group than in the late LTME group, postoperative morbidity and histopathological results did not differ between the groups.

CONCLUSIONS: The RTME group experienced a shorter learning period in comparison to early LTME group. The short-term outcomes in the RTME group were comparable to those of the late LTME group with exception of total operative time. Therefore, our experience shows that RTME is safe, can easily be learned, and is reproducible during the initial learning period even in complicated rectal cancer patients.

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