Introduction

The incidence of gastrointestinal neuroendocrine tumors (NETs) is increasing worldwide with the most frequent localization being the midgut. While guidelines have been proposed for the management of small bowel NETs, few evidences exist on the optimal treatment of NETs arising in the right colon and terminal ileum next to the ileocecal valve.1, 2 Despite biological differences, these tumors share a common route of lymphatic drainage along superior mesenteric axis. Therefore, we will refer to these tumors as terminal midgut NETs (TM-NETs).

The optimal extent of lymphadenectomy for midgut NETs remains debated, but growing evidences indicate that extended lymphadenectomies may improve survival and reduce symptoms associated to the presence of bulky nodes.3, 4

In our practice, the surgical approach for TM-NETs does not differ from that for locally advanced right colon cancers, in which a laparoscopic complete mesocolic excision (CME) right hemicolectomy (CME-LRH) represents the standard.5 We present the first series of CME-LRH performed as treatment of TM-NETs. A short video exemplifies the oncological principles and demonstrates the surgical technique.

Materials and Methods

Data from patients who underwent CME-LRH for TM-NETs, between September 2014 and November 2019 at the Unit of General and Hepatobiliary Surgery, University of Verona Hospital Trust, ENETS Center of Excellence, were retrospectively analyzed.

The study was approved by the local ethic committee and informed consent obtained from all the patients.

Results

Over the study period, 31 cases of midgut NETs were surgically treated at our institution. Figure 1 shows the flow diagram with patients’ selection details.

Fig. 1
figure 1

Consolidated Standards of Reporting Trials (CONSORT) diagram detailing the study inclusion criteria for patients with midgut neuroendocrine tumors (NETs)

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Study population data are shown in Table 1. Median age was 73 (range, 17–88) years; 7 females and 2 males were included. Most of patients presented with abdominal discomfort with underlying obstructive symptoms, anemia or positive fecal occult blood test; none showed signs and symptoms of carcinoid syndrome.

Table 1 Study population characteristics
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Surgery was performed with curative intent in 7 cases, while surgical debulking was the purpose in 2 metastatic cases.

All procedures were performed by a single surgeon (C.P.) according to a standardized approach (Video). Specimen extraction was obtained through an intra-umbilical incision with the purpose of exploring the entire length of small bowel. Median surgical time was 215 min (range, 160–294); median blood loss was 40 mL (range, 30–100). No conversion to open surgery occurred.

Histopathological examination revealed a G1 NET in 8 cases and a neuroendocrine carcinoma (Ki67 95%) in one case. No multiple localizations were observed, median tumor diameter was 28 mm (range, 8–50), and all but one patient had positive nodes (median 5, range 0–6). Median number of harvested lymph nodes was 21 (range, 11–31).

No post-operative mortality was observed, and post-operative course was uneventful in all except one case. Median length of stay was 4 days (range, 4–18).

At a median follow-up time of 18 months (range, 6–50), none of the patients suffered from mesenteric locoregional recurrence and all R0 resected patients were disease-free. The patient with diagnosis of carcinoma died from myocardial infarction 24 months after surgery.

Discussion

Mesenteric lymphatic metastases, usually presenting as bulky conglomerates of multiple LNs with desmoplastic retraction of the mesentery, can be found in up to 80% of patients with midgut NETs. Despite the advanced stage at diagnosis, midgut NETs are characterized by a favorable prognosis. Both in the context of curative and debulking surgery, complete resection of the primary tumor has demonstrated to improve survival and prevent complications related to bulky nodal disease.6, 7

We believe that, in considerations of the major role of nodal involvement and the encouraging results of the present series, the value of CME-LRH in the treatment of TM-NETs should be further investigated.