CORRELATION BETWEEN ALTERED EXPRESSION OF RETINOBLASTOMA PROTEIN AND CLINICAL OUTCOME IN PATIENTS WITH GASTRIC-CANCER

We studied the expression of RB protein in 136 endoscopically obtained biopsied materials from primary gastric cancers by means of immunohis tochemistry. The expression of RB protein was variably observed in the nuclei of tumor cells. Tumors could be divided into two groups. Group 1 (RB-positive) comprised 74 tumors (54%) that expressed RB protein i n 20% or more of tumor cells, and Group 2 (altered RB) included 62 tum ors (46%) that showed RB immunoreactivity in less than 20% of tumor ce lls. RB-positive tumors (Group 1) were more frequently observed in the early cancers (74%, 28/38) than in advanced ones (48%, 46/98). The in cidence of distant metastases was higher and involvement of serosa or lymph nodes was more frequently observed in Group 2 than in Group 1. I n addition, patients of Group 1 survived significantly longer than tho se of Group 2 (p<0.05). However, no correlation could be found between RB tissue status and proliferative activity. These results indicate t hat tumors with decreased RB-protein expression may have more aggressi ve biological behavior than tumors showing high expression of this pro tein.