Gut Microbiota And Radiotherapy

Inclusion Criteria: * Patient is planned to receive Stereotactic Body Radiotherapy (SBRT) to a lung lesion (either presumed or biopsy-proven NSCLC * Age 18 years old or older * Patient capable of giving informed consent Exclusion Criteria * Use of antibiotics, antifungal, antivirals or antiparasitics during the 4 weeks prior to registration * Active infection with oral temperature \>100°F * Use of corticosteroids, methotrexate or immunosuppressive drugs during the 4 weeks prior to registration * Use of chemotherapy during the 4 weeks prior to radiotherapy or during radiotherapy. Chemotherapy cannot begin before the collection of the 30-day post treatment sample (S4). * Confirmed or suspected HIV, HBV or HCV * Chronic constipation (bowel movements less frequent than every other day) * Active uncontrolled gastrointestinal disorders such as inflammatory bowel disease, moderate/severe irritable bowel syndrome, persistent, infectious gastroenteritis, colitis or gastritis, persistent or chronic diarrhea of unknown etiology, Clostridium Difficile infection (recurrent) or Helicobacter Pylori infection (untreated) * Major surgery of the GI tract, with the exception of cholecystectomy and appendectomy, in the past five years. Any major bowel resection at any time * Patients on anti-diarrheal medications * Patients on probiotics