Monitoring The Early Biologic Response Of Esophageal Carcinoma After Irradiation With F-18-Flt: An In-Vitro And In-Vivo Study

ObjectiveThe aim of our study was to explore the value of 3-deoxy-3-[F-18]fluorothymidine (F-18-FLT) and F-18-FLT PET in monitoring the early biologic response of esophageal carcinoma after irradiation in vitro and in vivo.MethodsAfter 2, 4, and 8h of irradiation at different doses (0, 5, 10, and 15Gy) of esophageal carcinoma cells in vitro, the uptake ratio of F-18-FLT, the relative cell survival rate, and ATP levels were measured. The tumor uptake ratio of F-18-FLT [tumor-to-nontumor (T/NT)] was measured through PET scans before and on the first, seventh, and 15th day after irradiation. The expression of proliferating cell nuclear antigen and Ki-67 was determined in both untreated and treated tumors.ResultsCompared with the control group, the uptake ratio changes of F-18-FLT after 2h of irradiation with 5Gy showed no statistical significance (3.650.17 vs. 4.00 +/- 0.17%, P>0.05), whereas the uptake ratios of the other groups decreased notably (F=33.93, P<0.01). The differences in the relative survival rates were not statistically significant (F=4.02, P>0.05). Linear regression analysis indicated a significant correlation between F-18-FLT and ATP levels (r=0.89, P<0.01). On F-18-FLT PET scan images of the xenografts, the baseline uptake ratio (T/NT) was 2.24 +/- 0.06. It decreased to 1.99 +/- 0.09, 1.85 +/- 0.04, and 1.15 +/- 0.10 at 1, 7, and 15 days after irradiation with 10Gy. Tumor uptake of F-18-FLT was closely correlated with proliferating cell nuclear antigen and Ki-67 expressions (r=0.83, P<0.001, and r=0.88, P<0.001).ConclusionThe uptake changes of F-18-FLT in esophageal carcinoma cells and tumor xenografts may reflect the early biological response of esophageal carcinoma after irradiation. Thus, F-18-FLT PET may be potentially used to monitor the early response of esophageal carcinoma after radiotherapy.