Small Intestine Cancer

A rare condition in which cancerous tumors develop in the small bowel.  The most common types include adenocarcinoma, lymphoma, sarcoma, and carcinoids.  All of these tumors have the potential to invade the bowel wall, spread into adjoining lymph nodes, and metastasize.

Incidence; Contributing Risk Factors

In developed nations, adenocarcinomas are most common whereas in developing countries, lymphomas are much more common.  At the start of the 21st century, doctors in the US were diagnosing only about 1,200 malignant small intestine tumors each year – a very small number compared to the frequency of tumors in other parts of the GI tract.

Put another way, cancer is 50 times more common in your large bowel than in your small bowel.  This may be due to several factors, such as the liquid nature of the contents of the small intestine (less irritation), the rapid transit time (less exposure time to toxic agents), the low bacteria count, or the alkaline pH.

Risk factors include the following:

• Adenocarcinoma of the small bowel is associated with Familial Polyposis Syndrome – an inherited disease in which the large bowel becomes carpeted by polyps of various dimensions during the second or third decade of life.  If untreated, the disease invariably leads to cancer of the colon or rectum.
• Alcohol abuse
• Consumption of salted or smoked meats and fish
• Heavy sugar intake

Signs and Symptoms

Like most GI cancers, early symptoms of small bowel cancer tend to be vague and nonspecific.  They may include abdominal discomfort associated with nausea, bloating and/or loss of appetite.

Symptoms of advanced disease include fatigue, weight loss, iron deficiency anemia, visible blood loss (vomiting blood or a material that looks like coffee grounds, or black stools), severe nausea and vomiting (because of the blockage caused by the cancer in the small bowel), jaundice (when the cancer involves the upper small intestine and blocks the bile ducts draining the liver).

Diagnosis and Tests

Doctors frequently diagnose small intestine cancer during surgery for unexplained bowel obstruction.  If cancer is suspected, doctors usually choose to perform a barium contrast study of the small intestine.  Upper GI tract endoscopy may be useful in detecting areas of concern in the immediate upper GI tract, and a CT scan of the abdomen or an abdominal ultrasound may help to visualize bulky tumors and to rule out any spread of the cancer to adjacent lymph nodes and distant organs such as the liver.  A colonoscopy may help diagnose tumors involving the lower areas of the small bowel.

Treatment and Prevention

Surgical removal is the primary treatment for cancer of the small intestine.  Chemotherapy or radiation therapy may be useful if the cancer is widespread; radiation therapy also may be helpful if there is widespread disease or if local tumors come back.  Surgery may relieve symptoms when the cancer has caused a bowel obstruction.  In this case, doctors may perform a bypass procedure or limited tumor removal.

Prevention:

• The association of small bowel cancer with underlying conditions makes it possible to identify populations at risk and to develop screening programs.
• People with a family history of polyp syndromes, such as Peutz-Jeghers and Gardner syndrome, may benefit from regular screening using upper GI tract barium studies.
• People with celiac disease are at higher risk of developing both adenocarcinoma and lymphoma of the small bowel.  They need to maintain a gluten-free diet.
• People with celiac disease who also have new onset weight loss, diarrhea, or abdominal pain need immediate medical attention, including possible CT scan of the abdomen and barium study of the small bowel to rule out cancer.
• People with Crohn's disease and small bowel bypass procedures also require immediate attention.
• Crohn's disease-related adenocarcinoma frequently develops in the lower end of the small bowel, making colonoscopy a potentially useful screening tool.

Prognosis

Fewer than 35% of people who have adenocarcinoma of the small bowel have a live more than 5 years after diagnosis.  Survival chances are better if the cancer is limited to the inner walls of the small intestine and the lymph nodes are not involved.  Chances are better still if the patient has a carcinoid tumor or lymphoma of the small bowel – these malignancies tend to respond better to chemotherapy and radiation treatment when doctors cannot completely remove the tumor.  The prognosis is poor, however, if there is a small bowel lymphoma alongside celiac disease or a weakened immune system.