Intersphincteric resection for very low rectal cancer: Clinical outcomes of open versus laparoscopic approach and multidimensional analysis of the learning curve for laparoscopic surgery

Background: Laparoscopic rectal cancer surgery is regarded as more complex because of its technical difficulties in pelvic exposure, dissection, and sphincter preservation. This study therefore aimed to investigate the feasibility of laparoscopic resection for low rectal cancer using intersphincteric resection (ISR) and to assess its short-term oncological outcomes. Further, we intended to analyze the learning curve for laparoscopic surgery and identify the factors influencing the learning curve. Methods: Patients with low rectal cancer who received open or laparoscopic ISR were retrospectively chart reviewed. The surgical and oncological outcomes were evaluated. Comparisons of operating time, estimated blood loss, surgical outcomes, and histopathologic status were analyzed. Also, operating time was used as a technical indicator for learning curve analysis. Results: The mean estimated blood loss was 265 mL (range, 100-800 mL) in the open group and 104 mL (range, 30-250 mL) in the laparoscopic group. There was a significant difference between these two groups (P <0.001). Operative experience analysis showed that the mean operating time was 402.1 min (range, 210-570 min) in the first stage and 331.4 min (range, 210-450 min) in the second stage, and on pathologic examination the mean number of lymph nodes harvested was 11.1 (range, 5-21) in the first stage and 18.3 (range, 11-31) in the second stage, with statistical differences between these two stages (P = 0.034 and P = 0.004, respectively). Multifactorial analysis showed that operating time was associated with surgeons' experience (