Cancerous (malignant) tumors in the small intestine are very uncommon, occurring in about 10,470 people in the United States each year. Adenocarcinoma is the most common type of cancer of the small intestine. Adenocarcinomas develop in the glandular cells of the lining of the small intestine. People with Crohn disease of the small intestine are more likely than others to develop adenocarcinoma.
Carcinoid tumors can develop in the glandular cells that line the small intestine. Carcinoid tumors often secrete hormones that cause diarrhea and flushing of the skin. Chemotherapy and other types of drugs sometimes help control the symptoms caused by carcinoid tumors.
Lymphoma (cancer of the lymphatic system) may develop in the middle section (jejunum) or the lower section (ileum) of the small intestine. Lymphoma may cause a segment of intestine to become rigid or elongated. This cancer is more common among people with untreated celiac disease. Chemotherapy and radiation therapy can help control symptoms and sometimes lengthen survival time.
Leiomyosarcoma (cancer of smooth muscle cells) can develop in the wall of the small intestine. Chemotherapy may slightly lengthen survival time after surgery to remove leiomyosarcomas.
Kaposi sarcoma is a type of skin cancer that can affect internal organs and sometimes occurs in people with AIDS due to human immunodeficiency virus (HIV) infection. Kaposi sarcoma can occur anywhere in the digestive tract but usually in the stomach, small intestine, or colon. This cancer usually does not cause symptoms in the digestive tract, but bleeding, diarrhea, and intussusception (one segment of the intestine slides into another, much like the parts of a telescope) may occur. Treatment of Kaposi sarcoma depends on where the cancer is but may include surgery, chemotherapy, and radiation therapy.
Adenocarcinoma may cause bleeding into the intestine, which shows up as blood in the stool, and obstruction, which in turn may lead to crampy abdominal pain, expansion (distention) of the abdomen, and vomiting. Sometimes cancers of the small intestine cause intussusception.
Doctors typically do enteroclysis. In this procedure, a large amount of barium liquid is inserted through a tube in the nose and x-rays are taken as the barium moves through the digestive tract. Sometimes this procedure is done with a computed tomography (CT) scan instead of plain x-rays, in which case the person can just drink the barium rather than having a tube put through their nose.
A doctor may use an endoscope (a flexible viewing tube—see Endoscopy) passed through the mouth and down to the duodenum and part of the jejunum (the upper and middle sections of the small intestine) to locate the tumor and perform a biopsy (remove a tissue sample for examination under a microscope). A doctor can sometimes see tumors of the ileum (the lower section of the small intestine) by passing a colonoscope (an endoscope used to view the lower part of the digestive tract) through the anus, through the entire large intestine, and up into the ileum.
A wireless battery-powered capsule that contains one or two small cameras (video capsule endoscopy) can be swallowed to show pictures of tumors of the small intestine.
Sometimes exploratory surgery is needed to identify a tumor in the small intestine.
The best treatment for most types of cancerous tumors in the small intestine is surgical removal of the tumor.
If doctors are able to see the tumor with an endoscope, they may also remove it by applying an electrical current (electrocautery), heat (thermal obliteration), or high-energy beam of light at the tumor (laser phototherapy).
Chemotherapy and radiation therapy after surgery do not lengthen survival time.