Etiology and Pathogenesis of Small Bowel Adenocarcinoma

  • Small bowel tumors are relatively rare:
    • Comprising only:
      • 5% of all gastrointestinal malignancies
  • Despite the small intestine being:
    • 75% to 80% of the total length of the gastrointestinal tract:
      • Small bowel adenocarcinomas are less common:
        • Than colorectal adenocarcinomas
          • This may be due:
            • To the more dilute and liquid small bowel contents
            • More rapid transit
            • Decreased bacterial load (compared to the colon):
              • Although the precise reasons for this low rate of malignancy are unknown
  • Estimated new cases and deaths from small intestine cancer in the United States in 2020:
    • New cases:
      • 11,110
    • Deaths:
      • 1,700
  • Adenocarcinoma (36.9%), lymphoma (17.3%), sarcoma (8.4%), and carcinoid tumors (37.4%):
    • Account for the majority of small intestine malignancies:
      • Which, as a whole:
        • Account for only 4% of all gastrointestinal malignancies
  • Small bowel adenocarcinomas:
    • Comprise approximately 37% of all small bowel malignancies:
      • And are the second most common small bowel cancer:
        • Slightly less common than small bowel carcinoid tumors (37.4%):
          • 9.3 per million new cases of small bowel carcinoid tumor annually in the United States
  • There are an estimated:
    • 7.3 per million new cases of small bowel adenocarcinoma annually in the United States
  • Small bowel adenocarcinomas:
    • Arise in men slightly more often than in women:
      • 53% versus 47%
    • The median age at diagnosis:
      • Is 67 years old
  • Small bowel adenocarcinomas:
    • Are thought to arise from adenomas:
      • But the details of this process are less well understood:
        • Than the natural history and biology of colorectal adenoma to adenocarcinoma development
    • There are several known risk factors for small bowel adenocarcinoma, including:
      • Familial syndromes:
        • Lynch syndrome
        • Familial adenomatous polyposis [FAP]
        • Peutz-Jeghers syndrome
      • Chronic inflammation:
        • Crohn disease
        • Celiac disease
      • Previous colorectal adenocarcinoma.

#Arrangoiz #SurgicalOncologist #CancerSurgeon #CancerExpert #SmallBowelTumors

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