Small Intestine Cancer

Small intestine cancer is a rare type of cancer that starts in the small intestine (small bowel)—the part of your digestive system that connects the stomach to the large intestine. The small intestine helps break down food and absorb nutrients. Even though it’s a long organ, cancers here are much less common than in the colon or stomach.

Because small intestine cancer can grow slowly and its symptoms may be vague, it’s sometimes diagnosed at a later stage. Signs can include abdominal pain, nausea, weight loss, anemia, or blood in the stool.

Doctors use tests like blood work, imaging scans, endoscopy, or biopsy to find and diagnose the cancer. Treatment depends on the tumor’s type, location, and whether it has spread, and may include surgery, chemotherapy, targeted therapy, or immunotherapy.

Types of small intestine cancer include:

• Adenocarcinoma: The most common type. It starts in the cells lining the inside of the small intestine, usually in the duodenum (the first part of the small intestine). It’s often linked to chronic inflammation or conditions like Crohn’s disease or celiac disease.
• Neuroendocrine Tumors (NETs): Slow-growing tumors that form in hormone-producing cells. These are one of the most common small bowel cancers and may cause symptoms like flushing or diarrhea if they release hormones.
• Lymphoma: A cancer of the immune system that can begin in the small intestine, especially in people with weakened immune systems. It often causes pain, bloating, or weight loss.
• Gastrointestinal Stromal Tumors (GISTs): Rare tumors that grow in the wall of the small intestine, often in the jejunum or ileum. Some are slow-growing; others are more aggressive.
• Sarcoma: Uncommon in the small intestine, these tumors form in connective tissue or muscle layers.

For more information about small intestine cancer, please visit the organizations listed below.