GISTs should be considered as potentially malignant tumors owing to their unpredictable recurrence and metastasis; however, there are no definite clinical criteria for the diagnosis and treatment of GISTs[9
]. EUS, especially an EUS-fine needle aspiration, plays an important part in the diagnosis of GISTs, can determine the nature of submucosal lesions of the digestive tract and is instructive in the choice of treatment methods. GISTs with a diameter of 3-5 cm shown in the endoscopic examination and by pathology are more likely to be malignant; therefore, such GISTs are supposed to be thoroughly surgically excised[10-14
]. Although large GISTs are more inclined to be malignant, the small ones also have the possibility, so it is irrational to regard tumor size as the only standard for the malignancy of GISTs[11,15
]. In this study, we defined the risk classification of GISTs according to the National Institutes of Health[16
]. Consequently, the GISTs with definite diagnosis should be treated as much as possible.
Nowadays, a variety of surgical methods (as well as chemotherapy) for the treatment of GISTs are recognized in foreign and domestic studies. Surgical operation is still the traditional treatment; many patients with GISTs have been reported as being excised by undergoing laparoscopy[17,18
], and it is significantly important to excise larger lesions by surgical treatment. Imatinib, a tyrosine kinase inhibitor, is currently being used to treat GISTs which have unique kinase mutations that serve as targets for medical therapy, but some disadvantages exist such as high cost of therapy, long-term treatment and indeterminate side-effects; meanwhile few studies are reported about the treatment for GISTs with unclear symptoms[19,20
]. However, endoscopic therapy for these is much rarer. Choosing the treatment for GISTs that has lesser invasive injury and lower cost under endoscopy is rather clinically valuable.
Endoscopic mucosal resection (EMR) can be applied to the treatment of patients with distinguishable lesions of the digestive tract, such as early carcinoma and submucosal tumor. Moreover, EMR has not only the same therapeutic effect as surgical operation, but a short operating time, short hospitalization time, rapid recovery and low medical costs. However, it is hard to accomplish en bloc resection by the use of EMR for those lesions whose size is 2 cm or more. As a result, the remains are likely to recur and lead to many complications such as bleeding and perforation. Compared with EMR, ESE is able to excise a large majority of GISTs and provide intact data for pathological diagnosis. For preoperative evaluation of benign stromal tumors whose size is 5 cm or less, ESE is able to accomplish en bloc resection. ESE fully demonstrates the superiority of minimally invasive surgery as it has the advantage of rapid recovery, short hospitalization time and low medical costs. In our study, ESE was preferable for the GISTs originating from the muscularis propria, but not from the muscularis mucosae.
ESE is appropriate for GISTs originating from the muscularis propria; however, too much air insufflation because of a long operating time leads to pain for the patients in various degrees after revival from anesthesia. Pain caused by abdominal distension is the most common type, resulting from gastrointestinal gaseous tension. Therefore, it is recommended to select inhaling CO2
instead of air, as the CO2
is easily soluble in blood and other body liquids. It is not only rapidly absorbed by the gastrointestinal tract, but easily eliminated from the body by respiration. Patients never appear to have a metabolic disorder such as CO2
retention. Yamano et al[21
] has reported that the usage of CO2
in enteroscopy could effectively alleviate the subjective pain of patients. In summary, our study investigated the comparison between the application of CO2
and air insufflation for the ESE operation; the postoperative subjective pain of patients was measured by VAS and results suggested that the absolute VAS was lower in the CO2
group than in the air group, and the number of patients with severe postoperative pain was also fewer in the CO2
We compared the value of PetCO2 at the following four time points: beginning of ESE, at total removal of the tumors, at completed wound management, and 10 min after ESE. From the above data, we could draw conclusions that there were no significant differences of PetCO2 at each time point between the two groups, suggesting that CO2 is not able to cause postoperative retention as well not influencing the safety during the operation.
Comparing postoperative anal exsufflation between the two groups, the results revealed that the time of anal exsufflation in the CO2 group is shorter than that in the air group, and that the flatus of patients in the CO2 group is also less, which demonstrates that CO2 is much easier to be absorbed. Both the difficulty of operation and the ratio of various related complications will increase in the case of the existence of a large amount of remaining gas.
The GISTs partly derived from muscularis propria are diagnosed as extraluminal type or clinging to the serosa by EUS. Those tumors clinging to the serosa layer cannot be excised completely by ESE; it is suggested to perform full-thickness excision and bring out a perforation initiative. In our study, there were five patients with full-thickness excision of GISTs who had little gas entry into the abdominal cavity so that there was less obvious abdominal pain, and no postoperative abnormal conditions happened compared with other patients by ESE. However, the patients with full-thickness excision among the air group had severe abdominal pain as well as long-term gastrointestinal decompression.
In summary, CO2 insufflation could effectively alleviate the pain of patients when the GISTs were excised by ESE, without the risk of CO2 retention. The safety of CO2 insufflation is comparable to that of air insufflation, and less pain exists after operation. Therefore, it is hopeful that CO2 insufflation will become the standard method for ESE with full-thickness excision and it is apparent that this method will be widely applied in the future.