Published online Jan 7, 2018. doi: 10.3748/wjg.v24.i1.87
Peer-review started: October 6, 2017
First decision: October 31, 2017
Revised: November 11, 2017
Accepted: November 27, 2017
Article in press: November 27, 2017
Published online: January 7, 2018
Endoscopic submucosal dissection (ESD) is a curative modality for mucosal-confined early gastric cancer (EGC) and its indications have been expanded. However, EGC tissues often present histological heterogeneity and comprise a mixture of several different cell types. The present criteria for ESD does not take consideration of the histological mixed-type EGC. The rate of lymph node metastasis (LNM) is the most important factor when deciding on endoscopic resection in ECG. Therefore, there is a current pressing need to clarify the relationship of histological mixed-type and the rate of LNM, and the feasibility of endoscopic resection for patients with histological mixed-type EGC confined in the mucosa.
According to the latest research, histological mixed-type EGC was associated with aggressive clinical features as well as poor outcomes, but these studies did not consider the different biological behaviors of the mucosal mixed-type EGC and submucosal mixed-type EGC. Given the mucosal undifferentiated EGC measuring less than 2 cm without ulceration has been included in the expanded criteria for ESD treatment, it is necessary to assess the feasibility of endoscopic resection for patients with histological mixed-type EGC confined in the mucosa.
In this study, we investigated the clinicopathologic features of EGC according to histological type classification to evaluate the biological behavior of mixed-type EGC and the predictive value of histological type on the rate of LNM in mucosa-confined EGC.
This study included 298 patients who underwent gastrectomy for EGC between 2005 and 2012. Enrolled lesions were divided into groups of pure differentiated (pure D), pure undifferentiated (pure U), and mixed-type according to the proportion of the differentiated and undifferentiated components observed under a microscope. We reviewed the clinicopathological features, including age, sex, location, size, gross type, lymphovascular invasion, ulceration, and LNM, among the three groups. Furthermore, we evaluated the risk factors for LNM in mucosal EGC.
Submucosal invasion, pure U type, and mixed-type were independent risk factors for LNM in EGC. The rate of LNM in mucosa-confined EGC was higher in the mixed-type group and pure U group than in the pure D group, but no significant difference was found between the mixed-type group and pure U group. Similarly, the rate of LNM in the submucosa-invasive EGC was higher in the mixed-type and pure U group than in the pure D group, but was not significantly different between the mixed-type and pure U group. Multivariate logistic analysis showed that histological type was not an independent risk factor for LNM in mucosa-confined EGC.
The distribution of tumor size, location, gross type, ulceration, lymphovascular invasion, and LNM rate were similar between the mixed-type group and pure undifferentiated group in mucosa-confined EGC, and the histological mixed-type was not an independent predictor of LNM in mucosa-confined EGC. According to the tumor-node-metastasis classification, the histological mixed-type and undifferentiated EGC could be managed in the same way, and curative ESD was feasible for patients with mucosal histological mixed-type EGC.
Endoscopic resection is a curative modality for EGC and its indications have been expanded. Our study indicated that the mucosal histological mixed-type EGC could be managed with curative ESD. With the gradual understanding of the pathogenesis and biological behavior of mixed-type EGC, more patients with mixed-type EGC would benefit from the ESD treatment.