Purpose:The efficacy of evaluation of changes of tumoral uptake of 3'-deoxy-3'-[~(18)F] fluorothymidine (FLT) was comparatively analyzed with that of ~(18)F-FDG at early stage after anticancer chemotherapy.Materials and Methods:Cells derived from human lung adenocarcinoma were incubated with cisplatin (CDDP),5-fluorouracil(5-FU),doxorubicin (Dox),for 1,4,24 and 72h.The doses(CD-DP: 67 μM; 5-FU 1,540 μM;MTX: 440 μM;) were determined corresponding to a estimated 10% - 95% proliferation inhibition.The cells were allowed to recover before FLT or FDG being added into the culture media for 60 min.Cell counts,viability,estimated by MTT method,were used to evaluate the cytotoxic effects of chemotherapy.Results: FLT uptake was increased significantly at 1 and 4 h after treatment with 5-FU( 145 ± 12%,150 ± 14%,P <0.01).decreased at 24 h and 72 h.In contrast,FLT accumulation was significantly reduced at cytostatic concentrations of CDDP at different time.The uptake of FDG did not change significantly at early time points after treatment,but decreased at 72 h.Conclusion: The tumor cell uptake of FLT revealed specific changes depending on the auti-cancer drug used at much earlier time than FDG after chemotherpay.