Safety Trial of Antimicrobial Therapy and Precision Radiation Therapy in Patients With Oligoprogressive Non-small Cell Lung Cancer

This trial is studying whether taking antibiotics around the time of precision radiation therapy (called SBRT — a focused, high-dose form of radiation) affects how well the treatment works in patients with non-small cell lung cancer, potentially through changes to gut bacteria. **You may be eligible if...** - You are over 18 years old - You have non-small cell lung cancer (either confirmed by biopsy or suspected based on scans) - You are scheduled to receive SBRT or a similar ablative (high-dose focused) radiation treatment - You are able to give informed consent **You may NOT be eligible if...** - You have taken antibiotics, antifungals, antivirals, or antiparasitics in the 4 weeks before enrolling - You have an active infection with a fever - You have been on steroids, methotrexate, or other immune-suppressing drugs in the past 4 weeks - You recently had chemotherapy or will have it during the radiation period - You have a history of HIV, hepatitis B, or hepatitis C - You have uncontrolled inflammatory bowel disease, persistent diarrhea, or a recent C. difficile infection - You have had major bowel surgery in the past 5 years - You currently take anti-diarrheal medications or probiotics Talk to your doctor to see if this trial is right for you.