Published online Sep 28, 2020. doi: 10.3748/wjg.v26.i36.5450
Peer-review started: May 18, 2020
First decision: July 29, 2020
Revised: August 7, 2020
Accepted: September 8, 2020
Article in press: September 8, 2020
Published online: September 28, 2020
Processing time: 128 Days and 22.1 Hours
Endoscopic resection has become a mainstay therapy for early gastric cancers (EGCs). EGCs with very low risk of lymph node metastasis are indications for endoscopic resection. The risk of lymph node metastasis markedly differs according to the histological types.
Although the undifferentiated-type (UDT) component adversely affects the clinical course of EGCs, whether the UDT component within histological-mixed-type (MT) EGCs can be recognized preoperatively is not known. This is particularly important because accurate pretreatment diagnosis of the UDT component can help make the right treatment decision for EGC.
We investigated the feasibility of the preoperative diagnosis of the UDT component within MT EGCs.
This is a retrospective study using clinical data and samples from patients with EGCs treated by endoscopic submucosal dissection. Through histopathological examination, we investigated each lesion’s UDT component: (1) Whole mucosal layer occupation; (2) Exposure to the mucosal surface; and (3) Existence of a clear border between the differentiated-type and UDT components. We examined endoscopic images using magnifying endoscopy with narrow-band imaging to identify whether the endoscopic UDT component finding was recognizable within the area where it was present in the histopathological examination. The preoperative biopsy results and comparative relationships between endoscopic and histopathological findings were also examined.
Whole mucosal layer occupation of the UDT component and exposure of the UDT component to the mucosal surface were observed in 67.3% and 79.6% of samples, respectively. However, the preoperative endoscopic images showed that only 24.5% of MT EGCs revealed the UDT component within the area where it was present histopathologically. Histopathological UDT predominance was the single significant factor associated with the presence of the endoscopic UDT component finding (61.5% vs 11.1%, P = 0.0009). Combined results of the pretreatment biopsy and magnifying endoscopy with narrow-band imaging showed the preoperative presence of the UDT component in 40% of MT EGCs.
Accurate pretreatment diagnosis of the UDT component was hardly achieved even when pretreatment biopsy and diagnostic endoscopy were combined. However, the possibility of UDT predominance should be suspected when a lesion shows an endoscopic finding of the undifferentiated-type component.
Currently, endoscopic resection plays a significant role in both the diagnosis and treatment of MT EGCs. Future studies should seek novel UDT findings to distinguish MT EGCs from pure differentiated-type EGCs.