The aim of this study was to evaluate 3 methods of predicting exact tumor location: preop GFS, preop CT, and intraop Lap. We found that preop GFS measurements differed significantly from preop CT and intraop Lap measurements. We conclude that endoscopic clipping combined with preoperative CT is most useful for preoperatively predicting the location of early gastric cancers, and intraoperative gastroscopy-guided laparoscopy is also useful. However, preoperative GFS is not helpful because of the distension of the stomach during GFS.
Kitano et al. [5
] first described laparoscopy-assisted distal gastrectomy, in 1994, and this procedure is now frequently used to treat early gastric cancer in Japan and Korea. Kanaya et al. [6
] later reported delta-shaped anastomosis during Billroth type I totally laparoscopic distal gastrectomy (TLDG), and Takaori et al. [7
] described the successful use of intracorporeal Roux-Y reconstruction after TLDG. Two studies have reported that compared to laparoscopy-assisted distal gastrectomy, TLDG results in a superior postoperative recovery and shorter hospital stay, although it is more costly [8
]. However, a disadvantage of TLDG is that the operator can only assess the margins after resection. This means that if the resection margin is very short and/or positive for malignant cells, the operation may not only be longer, with increased risk and cost, it may also have to be converted from subtotal to total gastrectomy. For this reason, it is very important that the tumor site be precisely known, allowing for accurate planning of the operation.
We usually perform preop GFS to examine both the location of cancer and to confirm the results of the biopsy. We perform preop CT for staging purposes before routine preoperative examination. Intraoperative GFS frequently reveals that preoperative GFS data are inaccurate when the tumor is located on the side of the lesser curvature, or in the middle or upper part of the body. This is true even when the preop GFS measurements are made by an experienced endoscopist. In contrast, when the tumor is located in the lower body, the preop GFS data are usually quite accurate. This is because of the distension of the stomach during GFS. Supporting this interpretation is our finding that preop GFS values were about twice as great as Vis values.
Two-dimensional CT detects early gastric cancer at very low sensitivity, 20% to 53% [10
]. However, 3D CT, which permits fast scanning, the rapid infusion of intravenous contrast medium, and gastric wall filling, is associated with a markedly increased tumor detection rate, as high as 80% to 88% [12
]. This is because it images 2 or 3 layers of the enhanced gastric wall [15
]. In the Republic of Korea, the incidence of early gastric cancer is much higher than it was 10 years ago [16
]. This means that it is very important to precisely locate early gastric cancer before the operation, especially in cases of laparoscopic gastrectomy. However, the ability of CT to predict the location of early gastric cancer is limited, particularly if the cancer is located on the horizontally oriented portion of the gastric wall, such as the lesser or greater curvature; this is because of poor z-axis resolution and a partial volume averaging effect [17
]. In addition, CT detects flat and depressed or excavated tumors with more difficulty than protruding-type tumors, and it rarely detects tumors that are located in the gastric angle [15
We found that preoperative endoscopic clipping followed by CT scan was very useful for accurately predicting the tumor site. Indeed, while endoscopic clipping was initially developed to facilitate hemostasis during gastrointestinal bleeding, now it is also widely used as a marker for radiotherapy or for closing gastrointestinal perforations [20
]. Ryu et al. [23
] have also reported the usefulness of preoperative endoscopic clipping for predicting the location of early gastric tumors before open surgery. In addition, Hyung et al. [24
] have reported that placing an endoscopic clip proximal to the tumor is also useful for detecting the tumor intraoperatively by laparoscopic ultrasonography. Thus, preoperative endoscopic clipping is a very simple and useful method. However, if the tumor is located in the posterior of the stomach, the intragastric air can distort preoperative measurements of tumor location, in which case clipping should be accompanied by laparoscopic ultrasonography.
Preoperative clipping has also been reported to be useful for intraoperative gastroscopy [8
]. Tumor site can be readily detected by intraoperative endoscopy under laparoscopic guidance, and indeed, in our hospital, we intraoperatively confirm tumor site using this method. Although endoscopy is time consuming, the surgeon can easily perform it, and we have the endoscope in the operation room itself. However, because the tumor can be difficult to identify with an endoscope, an experienced endoscopist should be enlisted to perform preoperative endoscopic clipping. Other investigators preoperatively marked the location of the gastric tumor in the submucosal layer of the stomach with an India ink tattoo [7
]. However, while endoscopic tattooing with dye yields good results for colonic lesions, it has been associated with several complications, such as fat necrosis with inflammatory pseudotumoral formation or colonic abscess with localized peritonitis [23
]. Phlegmonous gastritis has also been reported after Indian ink marking in early gastric cancer, and the ink can also disappear [29
Before this study, we suspected that intraoperative laparoscopy would locate early gastric cancers preoperatively more accurately than either preoperative CT or preoperative GFS. However, we found that preoperative CT with endoscopic clipping was in fact the most accurate way to predict cancer location. The relative inaccuracy of intraop Lap can be attributed to gastric contraction and folding. Errors in intraop Lap cannot be avoided since it is difficult to obtain precise measurements by intraop Lap when the stomach is distended. This is why we endoscopically remove intragastric gas before making the intraop Lap measurements. We believe another cause is the rigidity of the handmade Nelaton ruler, which is problematic when measuring distances that include the curved stomach wall. However, intraop Lap remains highly useful for detecting tumors and determining resection margins.
Despite recent technological developments, preoperative endoscopic clipping, 3D reconstruction, and measurement of the distance of a tumor from the pylorus or gastroesophageal junction remains a complex and time-consuming procedure. We recommend limiting this method to early gastric cancers located in the middle body, especially those that are proximal to the angle on the side of the lesser curvature.
In conclusion, endoscopic clipping combined with CT gastroscopy is very useful for preoperatively measuring the location of early gastric cancers, which is helpful for planning laparoscopic gastrectomy