MUCIN ANTIGEN EXPRESSION IN GASTRIC CARCINOMAS OF YOUNG AND OLD ADULTS

The striking differences in the histological features of gastric cance rs in young and old adults have been thought to be related to differen ces in the biological behavior of these cancers. Recently a new gradin g system (Goseki's classification) showed that the prognosis of the pa tient is particularly related to the mucin content of the carcinoma. I n this study, we examined differences in mucin antigen expression in c ancers from young and old adults and whether antigen expression is rel ated to the clinical outcome. The expression of two mucin core protein s (DF3 antigen [MUC1 gene product] and MRP antigen [MUC2 gene product] and a mucin-type carbohydrate antigen [sialosyl-Tn; STn]) was examine d immunohistochemically in gastric cancers from 69 young adults (30 to 39 rears of age) and 110 old adults (80 to 89 years of age). The inci dence rates of the three histological types (tubular adenocarcinoma, p oorly differentiated adenocarcinoma, and signet-ring cell carcinoma) w ere different in the young and old adults. However, among the mucin an tigens examined, only DF3 showed significantly higher frequency of exp ression in the old adults, and the difference was seen only in tubular adenocarcinomas (young, 43%; old, 68%) and poorly differentiated aden ocarcinomas (young, 19%; old, 49%). In these two histological types, t here was no difference in the frequency of MRP or STn expression betwe en the young and old adults, although the old adults showed a high inc idence of intestinal metaplasia that was positive for both antigens. S ignet-ring cell carcinomas showed no significant difference in express ion rates of the three antigens in young and old adults, but there wer e significantly higher expression rates in young patients for both MRP (young, 67%; old, 65%) and STn (young, 71%; old, 57%) and a lower rat e of DF3 expression (young, 0%; old, 14%). In both young and old adult s, the patients with DFB-positive carcinomas showed significantly poor er survival than those without DF3 expression, whereas there was not s ignificant difference in the survival of the patient groups with posit ive and negative MRP or STn reactivity. In conclusion, the expression of DF3 was influenced by the age of patients and was related to the ou tcome. In contrast, MRP and STn expression was related more to the his tological pattern of the tumor than to the age of the patient and did not correlate with the outcome. Copyright (C) 1997 by W.B. Saunders Co mpany.