Circulating Tumor Cells (CTC) in Lung Cancer

Eligibility Details: Inclusion Criteria Cohort A (one-time blood sample) & Cohort B (multiple blood samples) - Histologically or cytologically confirmed lung cancer (both non-small cell lung cancer and small cell lung cancer are allowed) - Stage 4 NSCLC or extensive-stage SCLC - Newly diagnosed disease with no prior systemic therapy for advanced disease Note: Patients that have received prior adjuvant chemotherapy or prior chemoradiotherapy for earlier stage lung cancer are allowed if treatment was completed ≥3 months. - Age ≥ 18 years - Ability to understand and the willingness to sign a written informed consent document Cohort C (healthy volunteers) - Age > 18 years but ≤ 95 years at the time of consent - Subjects must be English-speaking - Must voluntarily sign the most current informed consent and HIPAA documents prior to study participation. - Have no prior history of malignancy in the past 2 years with the exception of basal cell and squamous cell carcinoma of the skin. Other cancers with low potential for metastasis, such as in situ cancers can also be enrolled as healthy volunteers. Inclusion of Women and Minorities Both men and women of all races and ethnic groups are eligible for this study.