Sigmoidoscopy

Studying Biomarkers in Tumor Tissue and Blood Samples From Patients Undergoing Chemotherapy and Radiation Therapy for Stage II or Stage III Rectal Cancer That Can Be Removed By Surgery

Testing for Safety and Colorectal Cancer Preventive Effects of ONC201

Efficacy and Tolerability of a New Oral Extended-Release Formulation Containing Parnaparin Sodium, Administered Add-on Therapy

FMT in Ulcerative Colitis-Associated Pouchitis

Testing Nivolumab and Ipilimumab With Short-Course Radiation in Locally Advanced Rectal Cancer

Therapy Adapted for High Risk and Low Risk HIV-Associated Anal Cancer

Testing the Addition of an Anti-Cancer Drug, Irinotecan, to the Standard Chemotherapy Treatment (FOLFOX) After Long-Course Radiation Therapy for Advanced-Stage Rectal Cancers to Improve the Rate of Complete Response and Long-Term Rates of Organ Preservation

FOLFOX, Botensilimab, and Balstilimab for the Treatment of Localized Rectal Cancer Before Surgery

Long-Term Treatment of Collagenous Colitis With Budesonide

Increasing Colorectal Cancer Screening in African Americans

Nivolumab After Combined Modality Therapy in Treating Patients With High Risk Stage II-IIIB Anal Cancer

Screening for Colorectal Cancer in Older Patients (PLCO Screening Trial)

The Altitude Inflammatory Bowel Disease Study

Mechanisms of Idelalisib-Associated Diarrhea in Patients With Relapsed Chronic Lymphocytic Leukemia, Indolent Non-hodgkin Lymphoma, or Small Lymphocytic Lymphoma

Abnormal Food Timing and Circadian Dyssynchrony in Alcohol Induced Colon Carcinogenesis

Microbiome-Mediated Gut Dysfunction in Non-Alcoholic Fatty Liver Disease

Fecal Microbiota Transplantation for Patients With Chronic Widespread Pain