Laparoscopic gastrectomy has become a standard surgical treatment for patients diagnosed with early gastric cancer in East Asia.1
Minimal invasiveness and post-surgical quality of life in patients with early gastric cancer have recently received much focus. As such, TLDG using intracorporeal anastomosis without a small skin incision is gaining popularity. This study analyzed the learning curve of TLDG and compared early surgical outcomes of TLDG and LADG after learning curve completion. We also conducted the comparison between before and after TLDG learning curve.
This analysis shows that the TLDG learning curves by the 2 surgeons were considered complete after 40 and 20 operations. We ascertained that 40 and 30 cases of operations by surgeons A and B, respectively, were the points of learning completion in the moving average method, whereas 30 and 20 cases by the surgeon A and B, respectively, were the points of learning completion in the CUSUM curves. The TLDG failure rate was higher for surgeon A (surgeon A vs. surgeon B, 13.2% vs. 8.5%). Hence, we selected 40 cases as surgeon A's learning period among the 40 and 30 cases from the 2 methods and 20 cases as surgeon B's learning period among the 30 and 20 cases from the 2 methods. In fact, surgeon B participated as a first assistant during the initial 20 TLDG cases performed by surgeon A. As such, surgeon B had the opportunity to learn practical technical tips for intracorporeal anastomosis, including appropriate retraction skills, the direction of the linear stapler, and how to handle the instruments best. These experiences of surgeon B quite likely resulted in the reduced learning period. Possible strategies to reduce the TLDG learning curve include assistance from other well-trained staff, close intraoperative supervision by an expert, completion of an animal workshop, and completion of simulator exercises for intracorporeal anastomosis.
Several LADG learning curve studies have been reported to date. These reports showed that experience in managing 40~60 cases of LADG with systemic lymphadenectomy for early gastric cancer was required to achieve proficiency and reach a learning curve plateau.6
In contrast, no studies have yet reported on TLDG learning curves. To our knowledge, this study is the first report to analyze the TLDG learning curve. We also analyzed the multidimensional learning curve using the moving average method and CUSUM. Multidimensional analysis of the learning curve is particularly useful, as its use allows several essential parameters to be put together in a single graph.4
Intraoperative identification of tumor location is a prerequisite for TLDG because of the need for appropriate planning of the extent of gastric resection. During LADG, surgeons can easily identify tumor locations and tumor-free margins under direct vision. However, it is impossible to localize a tumor directly in TLDG. We solved this problem by using intraoperative endoscopy. During the laparoscopic surgery, we performed simultaneous gastroendoscopy and could then mark the stomach wall with a felt-tip pen under both laparoscopic and endoscopic vision. Besides this, several methods have been reported to localize tumors during laparoscopic gastrectomy, such as intraoperative laparoscopic ultrasonography after preoperative endoscopic clipping,18
intraoperative portable plain radiography with endoscopic clipping,19
and endoscopic tattooing. 20
Another important finding of this study is that TLDG is a timesaving procedure. The mean operation time was significantly shorter in the TLDG group (300.2 min vs. 251.4 min; P<0.01). In our earlier study, we recommended the use of total laparoscopic procedures in patients with high body mass index values or thick abdominal walls.22
We believe that the mini-laparotomy skin incision and the process of securing a proper visual field during extracorporeal anastomosis are the major causes of this. However, these issues were not observed when we performed the intra-corporeal anastomosis. Lee et al.23
also reported that the intracorporeal Billroth II anastomosis time of TLDG was statistically shorter than that of LADG.
Overall and moderate to severe (ASCPC≥2) morbidity rates reduced significantly after learning curve completion. Morbidity rates (leakage, intra-abdominal abscess, bleeding, wound, and lung complications) decreased after learning curve completion as well. In particular, the decrease in intra-abdominal abscess rate was statistically significant (P<0.01). We defined intra-abdominal abscess as the presence of septic fluid in the abdominal cavity that resulted in pyrexia (body temperature >38
) and was confirmed by ultrasonography or CT.24
For beginners and inexperienced TLDG surgeons, it is difficult to manage technical problems related to intra-corporeal anastomosis properly and to prevent contamination by the bowel contents while making the entry hole with the stapler. These initial experiences could cause early morbidities such as leakage, bleeding, and intra-abdominal abscesses. Inexperienced surgeons should pay particular attention to using proper anastomotic reconstruction techniques to prevent the occurrence of intra-abdominal abscesses until they overcome this learning curve.
Our study has several limitations. First, it was retrospective and nonrandomized. The enrolled patients underwent a number of different surgical procedures (Billroth I vs. Billroth II and hand sewing vs. linear stapler anastomosis). These factors would reflect a selection bias. Furthermore, detailed analysis about the timesaving effect in TLDG was lacking. Despite these drawbacks, we can ascertain some advantages. To our knowledge, the present study is the first report on the TLDG learning curve. It provides practical information for inexperienced TLDG surgeons by comparing learning curve completion data. We analyzed LADG and TLDG learning curve completion data to elucidate the feasibility of this newly extending surgical procedure further.
In conclusion, the learning curve was considered complete after 40~60 cases of TLDG in the training phase. The use of TLDG for early gastric cancer after learning curve completion was feasible and timesaving compared with LADG.