Abstract
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Learning Objectives The aim was to learn whether 18F-FLT or 18F-FDG can be used complementally in monitoring biological characteristics of colorectal cancer (CRC).
The study was to evaluate whether 18F-FLT or 18F-FDG can be used complementally in monitoring biological characteristics of colorectal cancer (CRC). Recurrence of SW480 and SW620 tumor were constructed in nude mice by irradiation. Tumor growth, metastasis and recurrence status were observed. 18F-FLT or 18F-FDG small animal PET scan of SW480 and SW620 tumor-bearing mice were obtained before and after irradiation 20Gy. T/NT (tumor/non-tumor) using ImageJ software on reconstructed images. Tumor markers, Integrinβ3, HSP27, VEGFR2, and Ki67 were detected by Western-blot and Immunohischemistry. The growth of SW480 tumors was much faster than SW620 (t=3.332, P=0.004). Higher incidence of lung and liver metastases was noted in SW480 than SW620 (P=0.023) tumor bearing mice. In Micro-PET study, the T/NT of 18F-FLT between SW480 and SW620 differed significantly (3.65±0.51 vs 2.22±0.42, P<0.001). Integrinβ3, HSP27expression was higher, while VEGFR2 and Ki67 expression lower, in SW480 cells than SW620. The capability of metastasis in lung and liver was significantly correlated with 18F-FLT uptake in tumors (r=0.574, P=0.006) and with HSP27 (r=0.894, P=0.008), and Integrinβ3 expression (r=0.635, P=0.088). There was a closely negative correlation was found between 18F-FDG uptake and recurrence time (r=-0.801, P=0.028). Significant negative correlation also existed between Ki67, VEGFR2 expression and recurrence time (r=-0.864, P=0.013 & r=-0.844, P=0.017). 18F-FLT is more suitable to reflect higher metastatic potential, while 18F-FDG is more suitable to predict recurrence of CRC in mic. 18F-FDG and 18F-FLT PET imaging together would be helpful in better predicting biologic behavior of CRC