Inclusion Criteria:

1. Ability to understand and willingness to sign a written informed consent document.

2. Subject must have histologically confirmed stage III, or IV squamous cell carcinoma
of the head and neck whose primary origin was from the oral cavity, oropharynx,
hypopharynx, or larynx. Carcinoma must be staged using the American Joint Committee
on Cancer (AJCC) staging criteria version 6. Adequate tumor must be amenable to
biopsy via outpatient methods, therefore the majority of subjects will be those with
oropharyngeal lesions.

3. Subjects must be scheduled to receive combined chemo-radiotherapy treatment for their
standard cancer care. Treatment decisions will be made by the treating
otolaryngologist, radiation, and medical oncologists.

4. Males or females greater than or equal to 21 years of age. Squamous cell cancer of
the head and neck is exceedingly rare in children and not generally applicable to the
pediatric population.

5. Karnofsky score greater than or equal to 60% at time of screening.

6. Life expectancy of greater than 6 months.

7. Subject must have normal organ and marrow function as defined below:

- leukocytes greater than or equal to 3,000/microL

- absolute neutrophil count greater than or equal to 1,500/microL

- platelets greater than or equal to 100,000/microL

- total bilirubin within normal institutional limits

- AST(SGOT)/ALT(SGPT) less than or equal to 2.5 X institutional upper limit of
normal

- creatinine within normal institutional limits

- BUN within normal institutional limits

- PT and PTT < 2.0 X upper normal limits

8. The effects of FLT on the developing human fetus are unknown. For this reason, women
of child-bearing potential and men must agree to use adequate contraception (hormonal
or barrier method of birth control; abstinence) prior to study entry and for the
duration of study participation. Should a woman become pregnant or suspect she is
pregnant while participating in this study, she should inform her treating physician
immediately. A screening urine hCG will be administered to women of childbearing
potential before each FLT scan.

Exclusion Criteria:

1. Subjects who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for
nitrosoureas or mitomycin C) prior to entering the study or those who have not
recovered from adverse events due to agents administered more than 4 weeks earlier.

2. Subject may not be receiving any other investigational agents.

3. Subject with a Karnofsky score below 60.

4. Pregnant women are excluded from this study. FLT PET has the potential for
teratogenic effects. Because there are potentially unknown risks for adverse events
in nursing infants secondary to treatment of the mother with FLT, breastfeeding
should be discontinued if the mother is imaged with FLT and may not resume for 48
hours after the FLT imaging.

5. Subject with an inadequate marrow reserve as determined by history and/or the above
tests.

6. Subject with a bleeding or clotting dysfunction as determined by medical history and
above tests.

7. Subjects taking nucleoside analog medications such as those used as antiretroviral
agents.

8. Inadequate tumor volume to allow for 2 biopsies.