Treatment of Duodenal Neuroendocrine Tumors

Duodenal neuroendocrine (carcinoid) tumors are rare, and there is no consensus on the optimal extent of surgical treatment.[1] In a retrospective review of 24 patients with a pathological diagnosis of duodenal neuroendocrine tumor, most tumors (89%) measured smaller than 2 cm in diameter, and most (85%) were limited to the mucosa or submucosa. Lymph node metastases were identified in surgical specimens in 7 (54%) of 13 patients in whom lymph nodes were examined, including 2 patients with tumors smaller than 1 cm, which were limited to the submucosa. At a mean follow-up of 46 months, the disease-specific survival rate was 100%, and only 2 patients had recurrences in regional lymph nodes. No patient was reported to have distant metastases or the carcinoid syndrome.[1][Level of evidence C1] The authors concluded that although duodenal neuroendocrine tumors are indolent, the presence of regional lymph node metastases cannot be predicted reliably on the basis of tumor size or depth of invasion, and their impact on survival is unclear.

In general, endoscopic excision of primary duodenal neuroendocrine tumors appears to be most appropriate for tumors smaller than 1 cm.[1] Duodenal neuroendocrine tumors smaller than 2 cm may be excised locally; for tumors between 1 cm and 2 cm, complete resection is ensured by operative full-thickness excision.[1,2] Follow-up endoscopy is indicated. Tumors larger than 1 cm may be difficult to remove completely endoscopically and should be evaluated with endoscopic ultrasonography before endoscopic resection is attempted because of their potential to invade beyond the submucosa.[3]

Appropriate management of tumors larger than 2 cm can be problematic.[2] However, in general, these tumors can be treated with operative full-thickness excision and regional lymphadenectomy. Lymphadenectomy is performed even in the face of negative preoperative imaging because of the high rate of lymph node metastasis for these tumors.[1]

In addition, some authors recommend that for tumors larger than 2 cm, a regional lymphadenectomy includes the lymph nodes in the following locations:

Regardless of the size of the primary tumor, abnormal lymph nodes detected on pretreatment imaging studies or at the time of surgery should be resected. Because little is known about the natural history of unresected, grossly evident lymph node metastases, nonoperative management might otherwise be supported. Node-positive patients should undergo continued radiographic surveillance regardless of the size of the primary tumor.[1]

Ampullary and periampullary duodenal neuroendocrine tumors deserve special consideration because they differ clinically, histologically, and immunohistochemically from neuroendocrine tumors that occur elsewhere in the duodenum.[5] Although their rarity precludes the establishment of any definitive natural history, these tumors appear to behave unpredictably and might be viewed as a distinct category of carcinoid tumor when treatment options are being considered.[2] Compared with tumors in other duodenal sites, even small (<1 cm) ampullary and periampullary neuroendocrine tumors exhibit distinctly different aggressive behavior, and they may metastasize early.[5,6]