Small Bowel Adenocarcinoma

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Synonyms

SBA,

Overview

Small bowel adenocarcinoma (SBA) is a rare malignancy of the gastrointestinal tract. However, these tumors are among those with worst prognosis. Vague clinical signs and symptoms and radiological diagnostic challenges often delay treatment, which negatively impacts the prognosis of the patients. However, recent advances in imaging technology, like multidetector computed tomography, magnetic resonance imaging, and capsule endoscopy, have made earlier and accurate diagnosis possible. Surgery is the treatment of choice followed by adjuvant therapy. However, there are no strict treatment guidelines available for the management of SBA. Most of the available evidence from colorectal and gastric carcinoma has been extrapolated to adequately manage SBA. Prognosis for SBA is better than gastric carcinoma but worse than colorectal carcinoma. Currently, there is not enough information on the molecular characteristics and tumor pathogenesis. Because the incidence of SBA is very low, there is a need for further studies to evaluate the possible application of newer investigative agents and strategies to obtain a better outcome within the framework of international collaborations.

Symptoms

Symptoms of small bowel cancer include:

  • Abdominal pain.
  • Yellowing of the skin and the whites of the eyes, called jaundice.
  • Feeling very weak or tired.
  • Nausea.
  • Vomiting.
  • Losing weight without trying.
  • Blood in the stool, which might look red or black.
  • Watery diarrhea.
  • Skin flushing.

Causes

The cause of small bowel cancer isn’t known. What’s known is that something happens to cells in the small bowel that changes them into cancer cells.

Small bowel cancer happens when cells develop changes in their DNA. A cell’s DNA holds the instructions that tell the cell what to do. The changes tell the cells to multiply quickly. The cells continue living when healthy cells would die as part of their natural life cycle. This causes too many cells. The cells might form a mass called a tumor. The cells can invade and destroy healthy body tissue. In time, the cells can break away and spread to other parts of the body.

Prevention

It’s not clear what may help to reduce the risk of small bowel cancer. If you’re interested in reducing your risk of cancer in general, it may help to:

  • Eat a variety of fruits, vegetables and whole grains. Fruits, vegetables and whole grains contain vitamins, minerals, fiber and antioxidants, which may help reduce your risk of cancer and other diseases. Choose a variety of fruits and vegetables so that you get different vitamins and nutrients.
  • Drink alcohol in moderation, if at all. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
  • Stop smoking. Talk to a health care professional about ways to quit that may work for you.
  • Exercise most days of the week. Try to get at least 30 minutes of exercise on most days. If you’ve been inactive, start slowly and build up gradually to 30 minutes. Also, talk to your health care team before starting any exercise program.
  • Maintain a healthy weight. If you are at a healthy weight, work to maintain your weight by combining a healthy diet with daily exercise. If you need to lose weight, ask your health care team about healthy ways to achieve your goal. Aim to lose weight slowly by increasing the amount of exercise you get and reducing the number of calories you eat.

Diagnosis

Multiple imaging techniques are available to evaluate small bowel neoplasms but the best imaging strategy is still not clear. Plain abdominal X-rays may show partial or complete obstruction; however, they are of limited value. Upper gastrointestinal series with small bowel follow-through involves administration of barium to delineate the small bowel and to pick up mucosal abnormalities; however, it does not contribute to staging and may miss smaller lesions. Enteroclysis provides improved and detailed evaluation of small bowel segments and can be performed by three methods : single contrast, air contrast, and methylcellulose enteroclysis. A thin nasogastric tube is passed beyond the stomach into the small bowel. However, enteroclysis is time-consuming, technically complex, and causes discomfort to the patient, and the procedure may miss flat infiltrating lesions and extramural disease.

Computed tomography (CT) scans are routinely done to detect abnormalities in small bowel, extramural spread of disease, and to rule out lymphatic and distant metastasis. The oral contrast agent is selected based on the anatomical area of interest in the small bowel and on the clinically suspected diagnosis for a particular patient. The radiographic findings differ with the location of the SBA and therefore aid in diagnosis. Duodenal carcinomas are seen as polypoidal, well-delineated lesions, whereas jejunal and ileal carcinomas are seen as annular narrowing with abrupt concentric or irregular overhanging edge stenosis that could lead to partial or complete obstruction. Moderate heterogeneous enhancement is usually seen after intravenous contrast administration. The absence of comb sign and the presence of a single focal lesion rather than multiple skip areas of bowel wall thickening differentiate adenocarcinoma of the ileum from Crohn’s disease

Prognosis

Small intestinal adenocarcinomas have a poor prognosis, with 5-year overall survival (OS) rates of 30.0% to 79.0% for localized disease and 3.0% to 19.0% for metastatic disease. This poor prognosis is partly due to diagnostic delay related to vague symptoms.

Treatment

Surgery remains the treatment of choice for localized SBA. Complete resection with negative margins with adequate lymph node dissection is the mainstay of treatment. The principle of surgical resection is to remove the tumor with at least 5 cm proximal and distal margin, with resection of the adjoining mesentery and adequate lymph-node dissection. The technique and type of resection depend on the segment of small bowel involved. Segmental resection with lymph node dissection is the treatment of choice for tumors located in jejunum and ileum. Lymphatic drainage of ileum and jejunum is to mesenteric nodes, which include superior mesenteric nodes. Tumors of the distal ileum or ileocaecal valve require ileo-caecal resection or right hemicolectomy with resection of ileocolic artery and associated lymph nodes[]. The lymphatic drainage of the ileocecum is to appendicular, ileocolic, and superior mesenteric lymph nodes. Segmental resection with lymph node dissection can be performed for tumors of first and third part of duodenum. For adenocarcinoma arising from the second part of duodenum or invading into the ampulla or pancreas, pancreaticoduodenectomy should be considered[]. Lymphatic drainage of duodenum is to pancreaticoduodenal, pyloric, hepatic (pericholedochal, cystic, hilar), and superior mesenteric nodes.

Harvesting eight lymph nodes are considered adequate for lymph node evaluation. Extended lymph node dissection does not appear to be beneficial in small bowel cancers.