Malignant tumors of the small intestine.

Primary malignant tumors of the small intestine are uncommon. The average annual incidence rate over a period of 30 years in Saskatchewan was 0.7 and 0.6 per 100,000 for male and females, respectively. The 209 patients who comprise the series represent 1.6% of the total number who had gastrointestinal cancers over the same period. The distribution of the tumors by site and histologic type is described. Both carcinoid and adenocarcinomatous tumors of the small intestine are associated with a high incidence of primary malignant neoplasms in other sites (17.0 and 20.3%, respectively). One patient with Peutz-Jeghers syndrome is of interest because of the malignant change which occurred in more than one of the small bowel polyps and because of consequent liver metastases. The reason for the poor prognosis in noncarcinoid small bowel malignant neoplasms is probably due to late diagnosis. The five-year disease-free survival in these tumors was 22.5%. Malignant carcinoids had a better overall five-year survival rate of 64%. For those confined to the bowel wall, the five-year survival rate was 73%, compared to 59% for those extending to nodes or metastasizing to distant organs.