Adenocarcinoma of the small bowel in lynch syndrome II.

Adenocarcinoma of the small bowel is rare and accounts for about 1% of all gastrointestinal tract cancer. This disorder has been identified in association with Crohn's disease, celiac disease, Peutz-Jegher's syndrome, and familial adenomatous polyposis. We report adenocarcinoma of the small bowel in nine patients from eight Lynch syndrome II extended pedigrees. Each affected patient was in the direct genetic lineage or manifested multiple primary cancers (stomach, colon, endometrium, and ovary) consonant with the tumor spectrum of Lynch syndrome II. The average age of onset for small bowel cancer was 47 years (range 31 to 56 years), versus the general population peak occurrence after the sixth decade. We conclude that small bowel cancer may be an integral component of the tumor spectrum of Lynch syndrome II.