A randomized phase II study of palliative radiation of advanced central lung tumors with intentional avoidance of the esophagus. Patients will be randomized between standard of care palliative thoracic radiation and esophageal-sparing intensity-modulated radiation therapy (ES-IMRT) in a 1:1 ratio. Radiotherapy will be administered as soon as possible following randomization and subjects will be followed for 1 year after completion of their radiation therapy. The primary endpoint is esophageal quality of life as measured by the Esophageal Cancer Subscore (ECS) of the Functional Assessment of Cancer Therapy-Esophagus (FACT-E).

Inclusion Criteria:

• American Joint Committee on Cancer (AJCC) 7th edition stage IV NSCLC or stage III not eligible for curative intent treatment
• Intended to receive palliative radiotherapy to the thorax, to a dose of 30Gy in 10 fractions or 20Gy in 5 fractions. In either treatment arm at least 5cm of the esophagus should be in the intended treatment field.
• Willingness and ability to provide informed consent
• Eastern Cooperative Oncology Group (ECOG) performance status 0-3
• Age 18 years or older
• Prior or planned systemic therapy (chemotherapy, immunotherapy, targeted agents) is permissible at the discretion of the treating medical oncologist, provided that no systemic treatment is given within 2 weeks prior to RT, concurrent with RT or within a 2-week period post RT.
• Concurrent palliative RT to other metastatic sites is permissible
• Life expectancy > 3 months

Exclusion Criteria:

• Prior thoracic RT
• Serious medical comorbidities precluding RT
• Pregnant or lactating women
• Inability to attend the full course of RT or planned follow-up visits
• Planned concurrent palliative RT to the stomach and/or liver
• Congenital abnormalities of the esophagus or severe disorders of the esophagus (e.g. achalasia)