Gastrointestinal cancer is when cancer develops in any part of the digestive system. Symptoms depend on which organ is affected, but can include vomiting, abdominal pain, loss of appetite, weight loss, jaundice, changes in bowel habits, and internal bleeding. These cancers are often diagnosed through tests like endoscopy, biopsy, and imaging scans like ultrasound, CT, and MRI. Treatment options include surgery, chemotherapy, and radiation therapy. It's important to catch these cancers early, so pay attention to subtle symptoms and get regular screenings as recommended by your doctor.