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Chin Clin Oncol. 2016 Feb;5(1):4. doi: 10.3978/j.issn.2304-3865.2016.02.03.

Neuroendocrine tumors (NETs) of unknown primary: is early surgical exploration and aggressive debulking justifiable?

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200 West Esplanade, Suite 200, Kenner, LA 70065, USA.
Department of Internal Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
Division of Surgical Oncology, Louisiana State University Health Sciences Center, New Orleans, LA, USA;
Department of Surgery, Ochsner Medical Center, New Orleans, LA, USA.
Division of Surgical Oncology, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
Neuroendocrine Tumor Clinic, Ochsner Medical Center, Kenner, LA, USA.



Neuroendocrine tumors (NETs) are rare tumors that often present with vague symptoms. Identification and localization of the primary NET can be challenging and the true incidence remains unclear. These patients have been thought to have a poor prognosis compared to those patients with a known primary. Therefore, traditionally the treatments for patients with unknown primaries have been passive and directed towards symptom control and/or cytoreduction of metastatic disease. We hypothesized that NET of unknown primary are predominantly low-grade and easily located surgically and therefore are amendable to surgical debulking and cytoreduction, which will likely increase survival in these patients.


The charts for all 342 surgical patients, seen in our clinic at Ochsner-Kenner between 1/2009 and 9/2012 were retrospectively reviewed to determine which patients had a pre-operative diagnosis of a "NET with unknown primary". Twenty-two patients (6.4%) were identified. For these patients, the rate of successful surgical exploration in which a primary site was identified was recorded. Survival for these "unknown primary" patients were compared to a large similar group of NET patients from a recent study collected from this same Ochsner clinic group.


Twenty-two (22/342, 6.4%) NET patients with a pre-operative diagnosis of an unknown primary were explored and cytoreduced. The primary tumor site was identified in all 22 patients (100%). The primary sites identified for these patients were 19 small intestines (86.4%) and 3 pancreatic (13.6%). All 22 patients had low-grade tumors and all were still alive as of 9/2012, not allowing for a survival curve to be generated.


Unknown primary NETs are not associated with a poor prognosis as previously reported. Timely surgical exploration and debulking always results in the identification of the primary and a maximum cytoreduction. Early surgical exploration with aggressive debulking is indicated for the treatment of these patients, as for the known counterpart.


Tumor of unknown primary; carcinoids; neuroendocrine tumor (NET)

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