Testing the Addition of an Immunotherapy Drug, Atezolizumab, to the Usual Chemotherapy Treatment During Radiation Therapy for Superior Sulcus Non-small Cell Lung Cancer

Inclusion Criteria: * STEP 1 RANDOMIZATION: Participants must have histologically confirmed cT3/T4, N0/1, M0 non-small cell lung cancer (NSCLC) of the superior sulcus arising in the apex of the lung, involving apical chest wall structures (parietal pleura and beyond) above the level of the second rib * STEP 1 RANDOMIZATION: Participants must have eligibility affirmed by a thoracic surgeon, medical oncologist and radiation oncologist. Participant must be a candidate for surgical resection and chemoradiation therapy. The site treating investigator must sign off to indicate that eligibility has been affirmed by each specialist * STEP 1 RANDOMIZATION: Participants may have measurable or non-measurable disease. Measurable disease must be assessed within 28 days prior to Step 1 Randomization. Non-measurable disease must be assessed within 42 days prior to Step 1 Randomization. All known sites of disease must be assessed and documented on the Baseline Tumor Assessment Form * STEP 1 RANDOMIZATION: Participants must have an MRI or CT scan of the brain (with contrast highly recommend) within 42 days prior to Step 1 Randomization * STEP 1 RANDOMIZATION: Participants must have a CT (chest with contrast highly recommended), contrast MRI (thoracic inlet), and FDG-PET/CT performed within 28 days prior to Step 1 Randomization * Note: DWI (Diffusion weighting imaging) is highly recommended on the MRI * STEP 1 RANDOMIZATION: Participants may participate in concomitant non-therapeutic trial…