METASTASIZING INTRAMUCOSAL GASTRIC CARCINOMAS - WELL DIFFERENTIATED TYPE AND PROLIFERATIVE ACTIVITY USING PROLIFERATE CELL NUCLEAR ANTIGEN KI-67

Background. Recently, endoscopic surgery for small superficial gastric carcinomas has become increasingly more challenging, and the treatmen t criteria remain controversial. Methods. To examine the metastatic po tential of intramucosal gastric cancers (IMGCs), IMGCs with regional l ymph node involvement (NI) were compared with IMGCs without regional l ymph NI clinicopathologically. To clarify the metastatic behavior of w ell differentiated adenocarcinoma (W-type), immunohistochemical staini ng using Ki-67 and proliferating cell nuclear antigen (PCNA) monoclona l antibodies were performed. Results. Of the 943 lesions with IMGC, 21 (2.2%) were NI on histologic examination. There was no significant di fference between the macroscopic classification and the incidence of N I. The sizes of the IMGCs with NI (median, 4.3 cm) were significantly larger than the IMGCs without NI (median, 2.4 cm). Among the histologi c grades classified according to the predominant features, the inciden ce of NI in poorly differentiated adenocarcinoma (P-type) (12/304, 3.9 %) was significantly higher than that in well differentiated (W-type) (6/489, 1.2%). Besides the 12 P-type IMGCs, 6 well and moderately diff erentiated type IMGCs contained some poorly differentiated components, totaling 18 IMGCs (86%) that were either mainly or partially P-type. Among the W-type IMGCs, the mean values of the Ki-67 and PCNA labeling indices (LI) for IMGCs with NI (Ki-67, 47.5%; PCNA, 58.3%) were highe r than those of the 25 randomly selected IMGCs without NI (Ki-67, 39.2 %; PCNA, 39.9%). Conclusions. The potential for NI in IMGCs seems to b e related closely to tumor size, the presence of poorly differentiated components, and, particularly in the W-type IMGC, the LI that are dem onstrated immunohistochemically with Ki-67 and/or PCNA.