Gastrointestinal lymphoma is a type of cancer that affects the lymphatic system in the gastrointestinal tract. It can occur in various parts of the digestive system, including the stomach, small intestine, and colon. This cancer arises from lymphoid tissue, which is responsible for immune responses. Symptoms may include abdominal pain, weight loss, and changes in bowel habits. Diagnosis typically involves imaging tests, endoscopy, and biopsy to confirm the presence of cancerous cells. Treatment options often include chemotherapy, radiation therapy, and sometimes surgery to remove affected areas. Early detection is crucial for improving outcomes.