Low-dose
therapy consisting of
cisplatin plus
5-fluorouracil was given to 20 patients with advanced
gastric cancer, and specimens were obtained to evaluate levels of
5-fluorodeoxyuridine (
FdUMP) and
thymidylate synthase (TS), indices of
DNA, and proliferating nuclear cell
antigen (
PCNA). There was a significant correlation between the levels of
FdUMP, total TS and free TS in
cancer and in normal gastric mucosa, respectively. Total TS of
cancer was higher than that of normal tissue, at 5.3 +/- 4.8 and 3.4 +/- 2.2 pmol/g, respectively. On the other hand, there was no relationship nor difference between The TSIR ratio of
cancer and normal mucosa. The
FdUMP levels of far advanced
cancer showed a tendency to be lower than those of the less advanced one, especially in liver
metastasis. The total TS was higher in intestinal type and in INF alpha or beta. The free TS was higher in invasive type, liver
metastasis and curability C. The TSIR ratio showed a tendency to be lower in far advanced cases, such as invasive type and INF gamma. The correlation between
DNA index and TS values and between
PCNA labeling index and TS values were good. These results suggest that TS levels would be a predictor for malignant potential as well as for chemosensitivity.