• There are 2 cohorts for this study. Cohort A & Cohort B are for patient subjects. Patients can participate in both cohorts simultaneously, or only one cohort per patient preference.
• The investigators anticipate that most patients who participate in Cohort B will also participate in Cohort A because Cohort A only requires a one-time blood draw at baseline.

Cohort A: 20 patients with NSCLC and 20 patients with SCLC. Blood samples will be collected from eligible patients only once at baseline. These samples will be immediately processed for CTCs and CTC derived xenografts.

Cohort B: 15 patients with NSCLC and 15 patients with SCLC. Blood samples will be collected from eligible patients at baseline just prior to initiation of therapy. Samples will also be collected on day 1 of every cycle of therapy for 4 cycles (typical cycles are 21 days for chemotherapy, 28 days for targeted therapy and 14 days for immune therapy). At the time of initiation of the treatment break, blood samples will be collected. During the treatment break, patients will be followed every 6-12 weeks with imaging studies, and we will collect blood samples at each visit. At the time of disease progression in the event patient goes on best supportive care, the last blood draw will be at the time of this decision as there will unlikely be any further imaging studies going forward. If a patient is found to have disease progression while on active therapy, the next blood draw will be on the first day of the next therapy and time point of subsequent blood draws will depend on the type of therapy the patient receives. The goal is to define whether CTC loads whether CTC loads predict symptoms, response, and disease recurrence.

For Cohorts A & B: Investigators will make every attempt to time the blood collection to coincide with blood collection for therapeutic purposes in order to minimize discomfort. Blood sample collection will take place either in the outpatient clinic, or while inpatient (at IUSCCC, Indiana University Hospital, or Eskenazi hospital). Patients can participate in both cohorts simultaneously, or only one cohort per patient preference.