Blood in the stool is a common symptom, but sometimes the cancer blocks the intestine, causing crampy abdominal pain and vomiting.
The diagnosis is based on various intestinal viewing techniques, including enteroclysis, endoscopy, and barium x-rays.
Surgical removal is the best form of treatment.
Cancerous (malignant) tumors in the small intestine are very uncommon, occurring in about 11,110 people and causing about 1,700 deaths in the United States each year. Adenocarcinoma is the most common type of cancer of the small intestine Small Intestine The duodenum is the first segment of the small intestine, and the stomach releases food into it. Food enters the duodenum through the pyloric sphincter in amounts that the small intestine can... read more . Adenocarcinomas develop in the glandular cells of the lining of the small intestine. People with Crohn disease Crohn Disease Crohn disease is an inflammatory bowel disease where chronic inflammation typically involves the lower part of the small intestine, the large intestine, or both and may affect any part of the... read more 
of the small intestine are more likely than others to develop adenocarcinoma.
Rare types of small-intestine cancer
Carcinoid tumors Carcinoid Tumors and Carcinoid Syndrome Carcinoid tumors are noncancerous (benign) or cancerous (malignant) growths that sometimes produce excessive amounts of hormone-like substances (such as serotonin), resulting in the carcinoid... read more 
(also called neuroendocrine 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. Some tumors can be removed surgically. Tumors that have spread can be controlled with drugs, such as somatostatin or everolimus, or with a treatment that involves the use of a radioactive somatostatin analog given by vein (this is called peptide receptor radioligand therapy or PRRT). Chemotherapy and other types of drugs sometimes help control the symptoms caused by carcinoid tumors.
Lymphoma Overview of Lymphoma Lymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs. Lymphomas are cancers of a specific type of white blood cells known as lymphocytes. These... read more 
(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 Celiac Disease Celiac disease is a hereditary intolerance to gluten (a protein found in wheat, barley, and rye) that causes characteristic changes in the lining of the small intestine, resulting in malabsorption... read more 
. 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 Kaposi Sarcoma Kaposi sarcoma is a skin cancer that causes multiple flat pink, red, or purple patches or bumps on the skin. It is caused by human herpesvirus type 8 infection. One or a few spots may appear... read more 
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 Intussusception Intussusception is a disorder in which one segment of the intestine slides into another, much like the parts of a telescope. The affected segments block the bowel and block blood flow. The cause... read more (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.
Symptoms of Small-Intestine Cancer
Adenocarcinoma may cause bleeding into the intestine Gastrointestinal Bleeding Bleeding may occur anywhere along the digestive (gastrointestinal [GI]) tract, from the mouth to the anus. Blood may be easily seen by the naked eye (overt), or blood may be present in amounts... read more 
, 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.
Diagnosis of Small-Intestine Cancer
Enteroclysis
Endoscopy
Video capsule endoscopy
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 Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT— see also Computed Tomography (CT)) and magnetic resonance imaging (MRI— see also Magnetic Resonance Imaging (MRI)) scans are good tools for assessing the size and location... read more (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 Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). Endoscopy can also be used to treat many disorders because doctors are able to pass instruments... read more ) 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 do 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 Video Capsule Endoscopy Video capsule endoscopy (wireless video endoscopy) is a procedure in which the person swallows a battery-powered capsule. The capsule contains one or two small cameras, a light, and a transmitter... read more ) 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.
Treatment of Small-Intestine Cancer
Surgical removal
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.
