Immunohistochemical detection of thymidylate synthase in advanced gastric cancer: A prognostic indicator in patients undergoing gastrectomy followed by adjuvant chemotherapy with 5-fluoropyrimidines

To investigate prognostic indicators for gastric adenocarcinomas in advance d stage, we have carried out immunohistochemical determination of thymidyla te synthase (TS) in carcinoma tissues. Sixty seven cases of curatively rese cted gastric carcinoma, under 70 years old at the time of surgery who had b een in the same grade of invasion and lymphnodal involvements (pT3/pN2, Sta ge IIIB), and had underwent postoperative 5FU-related chemotherapy far a lo ng period were extracted from the files of our hospital. Formulin-fixed and paraffin-embedded specimens were stained with an antibody for human TS (po lyclonal). A positive signal was always compared with some types of inflamm atory cells in the same slide because of their constantly strong signal. No rmal control tissue used was human bone marrow, containing blastic cells. B oth staining intensity and the fraction of positively stained carcinoma cel ls were examined in each case, and then the results were summarized with re spect to fraction of positively stained carcinoma cells. The present study indicates that the TS-negative group had better survival than the positive group (p<0.05), rite 5 Lear survival rates being 42.3% and 25.1%, respectiv ely which suggests that the frequency of TS-positive carcinoma cells could also be a prognostic indicator.