Small-Bowel Tumors

Small-bowel cancer accounts for an estimated 12,440 cases and approximately 2,090 deaths in the United States annually (1).

Benign tumors include leiomyomas, lipomas, neurofibromas, and fibromas. All may cause abdominal distention, pain, bleeding, diarrhea, and, if obstruction develops, vomiting. Polyps are not as common as in the colon.

Adenocarcinoma, a malignant tumor, is uncommon. Usually it arises in the duodenum or proximal jejunum and causes minimal symptoms. In patients with Crohn disease involving the small-bowel, the tumors tend to occur distally and in bypassed or inflamed loops of bowel.

Primary malignant lymphoma arising in the ileum may cause a long, rigid segment. Small-bowel lymphomas can arise in long-standing, untreated celiac disease.

Gastrointestinal neuroendocrine tumors (previously known as carcinoid tumors) occur anywhere in the gastrointestinal (GI) tract. They are most commonly identified in the small intestine, followed by the appendix, stomach, and rectum. The prognosis and treatment of these tumors depends on the site of origin and histologic features (particularly the differentiation of the tumor as related by the KI-67% index). Metastasis occurs frequently, with the liver being the most common site. Carcinoid syndrome arises from secretion of serotonin, histamine, or tachykinins into the systemic circulation causing episodic flushing and diarrhea, usually in cases of liver or retroperitoneal metastasis, whereby portal circulation (and thus liver metabolism of these substances) is bypassed.

Treatment varies significantly based on the site of origin. Small-bowel neuroendocrine tumors are surgically resected; repeat operations may be required, and, in many cases, more than one segment of small intestine is involved. Gastric neuroendocrine tumors, unlike those of the small intestine, can be managed with endoscopic resection if they are small and associated with chronic atrophic gastritis (eg, type 1 disease). Similarly, small rectal neuroendocrine tumors sometimes can be removed endoscopically. For metastatic neuroendocrine tumors, long-acting somatostatin analog therapy with dose escalation, peptide receptor radioligand therapy (PRRT) using a radiolabeled somatostatin analog, or everolimus can be used to effectively control the disease.analog, or everolimus can be used to effectively control the disease.

Kaposi sarcoma, occurs in an aggressive form in patients who are immunocompromised (eg, transplant recipients, patients with uncontrolled HIV infection). Lesions may occur anywhere in the GI tract but usually in the stomach, small bowel, or distal colon. GI lesions usually are asymptomatic, but bleeding, diarrhea, protein-losing enteropathy, and intussusception may occur. Treatment of Kaposi sarcoma depends on the cell type and location and extent of the lesions.