Duodenum cancer (small intestine cancer) is a rare type of cancer that forms in the uppermost part of the small intestine. There are four types of small intestine cancer. The first type is adenocarcinoma, this develops in the glandular cells that line the inside of the small intestine. The second type, sarcoma, develops in the muscle and other supporting tissues within the small intestine. The third type, carcinoid tumors, develop in the neuroendocrine cells of the small intestine and is slow-growing. The fourth type is lymphomas, they form in cells called lymphocytes within the small intestine. Some symptoms of duodenum cancer are abdominal pain, bloody stool, diarrhea, anemia, jaundice, and unexplained weight loss. Smoking, drinking alcohol, eating a lot or red/processed meat, having/had colon cancer, having Crohn’s or celiac disease, and being of older age are all risk factors for developing duodenum cancer.