The purpose of this study is to evaluate low oxygen areas called hypoxia within the tumor. These low oxygen areas are thought to be the reason why tumors are more resistant to radiation treatment. A tracer is an extremely small quantity of a substance. Tracer to which radioactivity has been attached may be used to "trace" events in the body. A tracer called iodo-azomycin galactopyranoside (or *IAZGP) appears to be able to detect low oxygen areas within tumor.

Radioactive iodine in this molecule can be detected by an imaging technique called a PET scan. This present study involves obtaining three scans using this new imaging technique. The goal of carrying out many scans is to determine which scan will best show any areas in your tumor that may have low levels of oxygen.

Inclusion Criteria:

• Patients must have locally advanced cancer as determined by currently accepted diagnostic work-up, including CT/MR/US.
• KPS >70%.
• Patients must be > or equal to 18 years of age.

Exclusion Criteria:

• Patients will be excluded from the study if they fulfill any of the following criteria:
• Patients with abnormal baseline thyroid function tests, or any thyroid disorder including but not limited to hypothyroidism and thyroiditis. Patients with thyroid cancer who have had a thyroidectomy are not excluded.
• Patients who are pregnant or lactating.
• Mental impairment that may compromise the ability to give informed consent and comply with the requirements of the study.
• Patients who cannot tolerate being in the PET scanner for the duration of the study.