Objective: We evaluated tumor hypoxia using F-fluoromisonidazole (F-FMISO) PET in relation to the expression of hypoxia-inducible factor-1α (HIF-1α) and p53 in patients with head and neck cancer and compared the results with those obtained using 2-deoxy-2-F-fluoro-D-glucose (F-FDG) PET.
Materials and methods: A total of 28 tumors (23 primary tumors and five metastatic lymph nodes) from 24 patients with newly diagnosed head and neck cancer were examined with F-FMISO PET and F-FDG PET. The F-FMISO PET images were scaled to the venous blood concentration of F-FMISO activity to produce tumor-to-blood (T/B) values. Hypoxia was defined as a region with a T/B ratio greater than or equal to 1.2. The maximum T/B (T/Bmax) and hypoxic volumes were calculated by region-of-interest analysis. For F-FDG PET, the maximum standardized uptake value (SUVmax) and hypermetabolic volume were calculated by region-of-interest analysis. The expressions of HIF-1α and p53 using immunohistochemistry were estimated in tumor tissue samples.
Results: A weak correlation was observed between hypoxic volume and T/Bmax (r=0.53, P=0.003) on using F-FMISO PET and between hypermetabolic volume and SUVmax (r=0.38, P=0.046) on using F-FDG PET. The hypoxic volume using F-FMISO PET and hypermetabolic volume using F-FDG PET also showed a weak correlation (r=0.44, P=0.020). The values of F-FMISO hypoxic volume showed a weak correlation with HIF-1α (r=0.40, P=0.037) and p53 (r=0.47, P=0.012) obtained on immunohistochemical examination.
Conclusion: This study demonstrates a weak correlation between hypoxic volume measured by F-FMISO PET and expressions of HIF-1α and p53 in head and neck cancer.