Cancer of the Small Bowel

Published on 04/03/2015 by admin

Filed under Hematology, Oncology and Palliative Medicine

Last modified 22/04/2025

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Cancer of the Small Bowel

Laura Doyon, Alexander Greenstein and Adrian Greenstein

Summary of Key Points

Incidence

• Small bowel tumors are rare, with incidence of less than 10% of new gastrointestinal cancer diagnoses and less than 1% of all new diagnosed cancers each year.

• Genes involved include APC and KIT and mismatch-repair genes.

Biological Characteristics

• Malignant small bowel tumors consist of carcinoid (37.4%), adenocarcinoma (36.9%), lymphomas (17.3%), and gastrointestinal stromal tumors (GISTs) (8.4%).

Staging Evaluation

• Staging is based on the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system. Gastrointestinal (GI) lymphoma is staged with the Ann Arbor system based on lymphatic and extra lymphatic involvement above and below the diaphragm.

Primary Therapy/Results

• Primary therapy for small bowel neoplasms is surgical resection. Appropriate lymphadenectomy must be performed for adenocarcinoma and carcinoid tumors.

Adjuvant Therapy

• Chemotherapy is often used for adenocarcinoma; however, there is no clear benefit for prognosis. GISTs are treated with tyrosine kinase inhibitors.

Treatment of Metastatic Disease

• Surgery may be used to control complications of local symptoms such as bowel obstruction. Chemotherapeutic options are being explored that do not have a clear benefit for prognosis as of this time.

Palliation

• Gastrointestinal bleeding, mechanical obstruction, pain, and perforation may require palliative surgery in situations when curative resection is not possible. The use of palliative chemotherapy is also being explored. Somatostatin analogs are used in carcinoid syndrome.

Self-Assessment Questions

1. What location is the most likely source of malignancy after colectomy for familial adenomatous polyposis (FAP)?

D Extraintestinal, i.e., desmoid

(See Answer 1)

2. What is the most appropriate treatment for an asymptomatic gastrointestinal stromal tumor (GIST) tumor located in the midjejunum, measuring 2.5 cm?

A Watch and wait

B Tyrosine kinase inhibitor only

C Segmental resection

D Segmental resection including mesenteric lymph nodes

(See Answer 2)

3. What is the most common type of small bowel malignancy?

A Adenocarcinoma

(See Answer 3)

1. Answer: A. Duodenal adenocarcinoma is the most common source of malignancy after colectomy in patients with FAP. Desmoid tumors are also common in this patient population, and although they are locally aggressive, they are not actually malignant tumors.

2. Answer: C. GISTs >2 cm should be resected; however, there is no role for regional lymph node resection, because spread via lymph nodes is rare.

3. Answer: D. According to the Surveillance, Epidemiology and End Results 2004 report, carcinoid tumors have now superseded adenocarcinoma in incidence: carcinoid 37.4%, adenocarcinoma 36.9%, lymphomas17.3%, stromal tumors 8.4%.

SEE CHAPTER 76 QUESTIONS

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