Trial Information

PET/CT to Image Hypoxia in Head and Neck Tumours

Patients with head and neck cancer greater than 3 cm will imaged with PET scan and CT scan
in order to determine areas of the tumour that are hypoxic. Following surgical removal,
samples of the tumour will be evaluated for the expression of hypoxia genes. The
preoperative imaging will be compared to the "gold standard" measures of hypoxic response at
the level of gene transcription and a new hypoxia marker with the hypoxyprobe detection
system (pimonidazole).

Hypothesis: FDG/PET visualization of glycolysis combined with CT visualization of blood flow
will correlate with cellular response to hypoxic stress in head and neck tumors and
intra-tumor regions. Measurement of relative levels of mRNAs encoding hypoxia response genes
will be performed in cells microdissected from the surgical samples. Good correlation
between imaging signals and direct molecular measures of hypoxic response in primary human
tumors will provide information necessary to develop treatment strategies that employ
targeted, increased radiation to hypoxic tumors.

Pimonidazole is an exogenous nitro-imidazole marker, which can be detected through
immunohistochemical analysis of frozen sections. It detects cellular hypoxia upon becoming
reduced in cells with low oxygen tension, a property that can be detected through antibody
mediated detection of the reduced form. It has also shown to reliably and specifically stain
hypoxic regions within the tumor, and to correlate well with patient prognosis and treatment
outcome.