Cancer of Small Intestine

Risk Factors

Each year, US doctors diagnose about 1200 malignant small intestine tumors. This is a small number relative to the frequency of tumors in other parts of the GI tract.

It has been proposed that the liquid nature of the small intestinal contents may be less irritating to the mucosa, the innermost lining of the small bowel.

Rapid transit time in the small bowel may reduce exposure of the intestinal wall to Cancer-inducing agents found in the intestinal contents.

Other factors that might limit the presence or impact of potential cancer-inducing agents include the following:

• A low bacterial count
• A large lymphoid tissue component in the wall of the small intestine
• An alkaline pH inside the small intestine
• The presence of the enzyme benzpyrene hydroxylase

Adenocarcinoma of the small bowel is associated with the following underlying conditions:

Crohn disease - An inflammation in the small intestine. Crohn disease usually occurs in the lower part of the small intestine, called the ileum. The inflammation extends deep into the lining of the affected organ, causing pain and making the intestines empty frequently, resulting in diarrhea.

Celiac disease - Gluten intolerance

Familial polyposis syndromes - 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. Celecoxib (Celebrex) has been Food and drug Administration (FDA) approved for FAP. After 6 months, celecoxib reduced the mean number of rectal and colon polyps by 28% compared to placebo (sugar pill) 5%.

Cancer is 50 times more common in the large bowel than in the small bowel. Risk factors in the general population include the following:

• Alcohol abuse
• Consumption of salted or smoked meats and fish
• Heavy sugar intake

Risk factors for developing cancer of the small intestine in Crohn disease include the following:

• Male sex
• Long duration of disease
• Associated fistulous disease: A fistula is an abnormal tube that passes from one surface to another, such as from the colon to the skin.
• Surgical removal of part of the bowel
• The risk of developing small intestinal Cancer is 6 times greater for people with Crohn disease compared to the general population.

Lymphoma of the small intestine is associated with celiac disease but is also strongly associated with weakened immune systems such as occurs with AIDS

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 disease and small bowel bypass procedures also require immediate attention.
Crohn disease -related adenocarcinoma frequently develops in the lower end of the small bowel, making colonoscopy a potentially useful screening tool.

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