PET-based analysis of tumor glucose metabolism and tumor hypoxia before and during anti-neoplastic treatment

Tumor hypoxia is an important contributor to chemo-radiotherapy resistance. This has been demonstrated in several tumor types including non-small cell lung cancer and head and neck squamous cell carcinoma. Tumor hypoxia is a dynamic process, some parts of the tumor exhibit higher levels of hypoxia than others due to differences in blood flow as a result of constantly changing tumor microenvironment. Therefore, precise delivery of higher radiation doses per fraction to the specific hypoxic sub-volumes of tumor identified by FAZA-PET imaging may improve the therapeutic ratio by increasing local tumor control without inducing excess radiation induced side effects. Therefore, it is necessary to identify spatio-temporal dynamics of tumor hypoxia during treatment. In our study, FAZA-PET imaging is able to detect heterogeneous distribution of hypoxic sub-volumes out of homogeneous FDG background in a tumor. Most importantly we observed relatively stable tumor hypoxia at FAZA-week 2 of chemoradiotherapy. Hence, FAZA-PET might be developed into a tool for guiding adaptive radiotherapy treatment planning. However, additional studies are needed on the spatial-temporal dynamics of tumor hypoxia, to stratify patients who may benefit from hypoxia based radiotherapy treatment planning before implementation