Molecular Basis of Adenocarcinoma of the Small Bowel

Individuals with colorectal adenocarcinoma are at increased risk for developing small bowel adenocarcinoma:
- Suggesting a possible common molecular pathway
Multiple mutations have been identified in small bowel adenocarcinomas:
- Many of which are also implicated in colorectal cancer:
  - However:
    - The sequential genetic alterations in small bowel adenocarcinoma are less well understood than for colorectal adenocarcinoma
Several familial syndromes:
- Are associated with increased incidence of small bowel adenocarcinoma:
  - Hereditary cancer syndromes including:
    - Lynch syndrome (hereditary nonpolyposis colorectal cancer)
    - FAP
    - Peutz-Jeghers syndrome:
      - All of this cancer syndromes are associated with elevated lifetime rates of small bowel adenocarcinomas:
        As high as 2% to 8%, 3% to 5% (mostly in the duodenum), and 13%, respectively

Chronic inflammatory conditions:
- Are also implicated in the etiology of small bowel adenocarcinoma, including:
  - Crohn disease
  - Celiac disease
    - The risk of adenocarcinoma in Crohn disease:
      - Is proportional to the extent and duration of small bowel disease:
        With 0.2% risk at 10 years and 2.2% at 25 years
        This is a 27- to 60-fold increased risk over the general population
  - Individuals with celiac disease:
    - Are also at 34-fold increased risk for small bowel adenocarcinoma than those without celiac disease

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Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO