Mismatched Intratumoral Distribution of [18F] Fluorodeoxyglucose and 3'‑deoxy‑3'‑[18f] Fluorothymidine in Patients with Lung Cancer

In a mouse model of human lung cancer, intratumoral distribution between 3'-deoxy-3'-[18F] fluorothymidine (18F-FLT) and [18F] fluorodeoxyglucose (18F-FDG) was mutually exclusive. 18F-FLT primarily accumulated in proliferating cancer cells, whereas 18F-FDG accumulated in hypoxic cancer cells. The aim of the present study was to evaluate these preclinical findings in patients with lung cancer. A total of 55 patients with solitary pulmonary lesion were included in the present study. Patients underwent 18F-FLT positron emission tomography-computed tomography (PET/CT) and 18F-FDG PET/CT scan with a 3-day interval. The final diagnosis was based on histological examination. Among the 55 cases, a total of 24 cases were confirmed as malignant lesions. Mismatched 18F-FLT- and 18F-FDG-accumulated regions were observed in 19 cases (79%) and matched in 5 (21%). Among the 31 benign lesions, 18F-FLT and 18F-FDG were mismatched in 12 cases (39%) and matched in 19 (61%). The difference in intratumoral distribution of 18F-FLT and 18F-FDG between malignant and benign lesions was statistically significant (P<0.05). The results of the present study indicate that a mismatch in intratumoral distribution of 18F-FLT and 18F-FDG may be a feature of patients with lung cancer. Increased 18F-FDG accumulation may serve as an indicator of tumor hypoxia, whereas regions with increased 18F-FLT uptake may be associated with an increased rate of cancer cell proliferation in patients with lung cancer.