Tubular adenoma and intramucosal intestinal-type adenocarcinoma of the stomach: what are the pathobiological differences?
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The concept of human early gastric cancer has discrepancies among pathologists worldwide. Recently, a novel morphological classification of gastrointestinal intramucosal neoplasias was proposed and conceptual differences have gradually decreased. However, there are few studies on the differences of pathobiological properties among the intraepithelial neoplasms. The aim of the present study was to clarify the clinicopathological significance of gastric intramucosal tumors from the pathobiological viewpoint.
Methods. This study analyzed 70 tubular adenomas (TAs) with mild or moderate atypia and 52 intramucosal intestinal-type adenocarcinomas (IMACs) of the stomach from the viewpoint of the apoptotic index (AI), Ki-67 labeling index (KI), and intratumoral microvessel density (IMVD), using immunohistochemistry and the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) method. We also examined the expression of P53 and thymidine phosphorylase (dThdPase).
Results. The mean AI was significantly higher and the mean KI and IMVD were significantly lower in the TAs than in the IMACs (P < 0.05, P < 0.001, and P < 0.01, respectively). AI and IMVD showed a negative correlation in TAs and IMACs (TAs; P = 0.015; r = 0.28; IMACs; P = 0.006; r = 0.41). dThdPase and nuclear P53 expression were significantly higher in the IMACs than in the TAs (P < 0.05, P < 0.01). Mean IMVD was significantly higher in dThdPase-positive tumors than in the negative ones (P < 0.01, P < 0.01) in both TAs and IMACs.
Conclusion. IMACs possess higher proliferative activity of tumor cells, with a vascular-rich microenvironment, than TAs. This might reflect the pathobiological differences between gastric IMACs and TAs, and could also provide useful information on indications for gastric endoscopic mucosal resection for IMACs as has been recommended by the Japanese Gastric Cancer Association.