The purpose of this study is to determine whether we can identify lung cancer cells circulating in the peripheral blood of lung cancer patients using cell surface markers found on cancer cells such as CD44 and epithelial specific antigen.

Inclusion Criteria:Inclusion Criteria (Cases):

1. Advanced stage (IIIB with malignant effusion or IV) histologically or cytologically confirmed NSCLC
2. Patients must be newly diagnosed (untreated) or have evidence of disease progression at the time of sample collection
3. ability to sign informed consent
4. at least 18 years of age

Inclusion Criteria (Controls):

1. no known prior or active malignancy
2. ability to sign informed consent
3. at least 18 years of age Exclusion Criteria:1. history of any other cancer other than non-melanoma skin cancer within the last 5 years

2. pregnant women