EFFICACY OF THE DIAGNOSTIC ACCURACY USING MAGNIFYING ENDOSCOPY WITH NARROW-BAND IMAGING FOR PURE SIGNET RING CELL CARCINOMA AND POORLY DIFFERENTIATED-TYPE COMPONENT MIXED WITH UNDIFFERENTIATED-TYPE ADENOCARCINOMA

Aims Intramucosal undifferentiated-type early gastric cancers measuring < 2 cm without ulcers or scars, are positioned for the expanded indication of endoscopic submucosal dissection (ESD). However, the undifferentiated-type have been reported to have low curative resection rates compared with the differentiated-type. We have already reported that pure signet ring cell carcinomas (pure-sig) have higher curability rates than undifferentiated-type adenocarcinomas component mixed with poorly differentiated-type (mixed-por). Mixed-por is an important factor for the non-curability of undifferentiated-type adenocarcinomas. Therefore, we investigated the diagnostic accuracy of magnifying endoscopy narrow-band imaging (ME-NBI) for pure-sig and mixed-por.

Methods We recruited 118 undifferentiated early gastric cancers in 116 patients treated with ESD between July 2005 and December 2016 at the Cancer Institute Ariake Hospital after excluding lesions in accordance with the exclusion criteria (62 mixed-por and 56 pure-sig lesions). The results of the biopsy, histological analysis of the ESD specimen, and ME-NBI findings were compared. ME-NBI findings were divided into two groups: those with or without irregular vessels. Using the ME-NBI combination method, mixed-por was diagnosed when the biopsy findings indicated mixed-por and/or it showed irregular vessels by ME-NBI.

Results 27/62 (43.5%) of final histological mixed-por lesions were diagnosed accurately by pre-treatment biopsy (p < 0.0001). 52/62 (83.9%) of lesions had irregular vessels detected using ME-NBI (p < 0.0001). Using the ME-NBI combination diagnostic method, a case that was mixed-por at pre-treatment diagnosis was confirmed in the final histological analysis (p< 0.0001). The sensitivity and accuracy rates were significantly higher in the ME-NBI combination group than in the biopsy group (p < 0.05).

Conclusions When we diagnose undifferentiated-type adenocarcinoma before ESD, the ME-NBI combination method will yield higher diagnostic accuracy for pure-sig or mixed-por compared to biopsy alone.