Early Prediction of Therapeutic Response to Targeted Therapy in Stage IIIB/IV or Recurrent Lung Cancer Patients

1. All subjects must be enrolled in the the therapeutic trial (IRB # 24377) with non-squamous non-small cell lung cancer (NSCLC) treated with combined erlotinib (Tarceva) (150 mg/day)and bevacizumab (Avastin) (15mg/kg q 21 days) as first line therapy. 2. Adults must have radiological evidence of Stage IIIB/IV or recurrent non-squamous non-small cell carcinoma. The Stage IIIB/IV or Recurrent lesion must be in a location that includes a large arterial vessel to allow for determination of the H215O arterial input function. A previous histological diagnosis of NSCLC would be required prior to institution of therapy. Only clinically indicated biopsy and/or surgery for determination of Stage IIIB/IV or recurrent disease will be done and surgery is incidental to inclusion in the protocol. 3. Patients must be 18 years or older for inclusion in this study. Since there is no experience with \[F-18\]FLT in children and it would be inappropriate to study individuals under the age of 18 until more safety data is available. 4. After entry into the study, patients are expected to be followed for at least 2 months as part of standard of care. 5. All patients, or their legal guardians, must sign a written informed consent and HIPAA authorization in accordance with institutional guidelines. 6. The patient, if female, must be postmenopausal for a minimum of one year or surgically sterile, or on one of the following methods of birth control for a minimum of one month prior to entry into this study: IUD, oral contraceptives, Depo-Provera or Norplant. These criteria can be waived at the discretion of the investigator if the patient's tumor is considered life threatening and the one month wait required is not in the best interest of the patient. Negative pregnancy test is accepted. 7. Pre-treatment laboratory tests for patients receiving \[F-18\]FLT must be performed within 21 days prior to study entry. These must be less than 4 times below or above the upper or lower limit range for the respective laboratory test. The patients have Stage IIIB/IV or recurrent NSCLC and therefore many routine laboratory tests may not be within the typical normal range. Using a factor of 4 times above or below the upper or lower value for the normal range for laboratory test will assure ability to recruit patients and maintain safety. In those instances where a value of 4X above the normal range would be inappropriate for inclusion (prothrombin time and partial thromboplastin time) then a value of 2.5X will be used for these two laboratory tests. In those instances when the prothrombin time or partial thromboplastin time are greater than 2.5X the upper limit of normal then such a patient would not be enrolled. The 4X value will be used for all laboratory values except prothrombin time and partial thromboplastin time which cannot be above or below 2.5 times the upper or lower limit of normal (Appendix E, \[F-18\]FLT Laboratory Study Results). A negative serum pregnancy test is required within 2 days prior to the PET studies. 8. Pre-treatment radiological clinical scans/studies (Gd- enhanced MRI or CT to document Stage IIIB/IV or recurrent NSCLC) must be performed within 30 days of study entry.

1. Patients will be receiving erlotinib (Tarceva) (150 mg/day)and bevacizumab (Avastin) (15mg/kg q 21 days) as part of the therapeutic trial. Enrollment may not occur if the patient does not meet the enrollment criteria for the therapeutic trial 2. Patients with known allergic or hypersensitivity reactions to previously administered radiopharmaceuticals. Patients with significant drug or other allergies or autoimmune diseases may be enrolled at the Investigator's discretion. 3. Patients who are pregnant or lactating or who suspect they might be pregnant. 4. Adult patients who require monitored anesthesia for PET scanning. 5. HIV positive patients due to the previous toxicity noted with FLT. 6. Claustrophobia or inability to remain stationary within the PET scanner for 90 minutes.