Branislav Klimàcek: Clinical Management and Outcomes of Small Intestinal and Appendiceal Neuroendocrine Tumours

Abstract

Small intestinal and appendiceal neuroendocrine tumours (SI-NETs and aNETs) are rare malignancies with specific surgical and oncological challenges. Despite increasing evidence, certain questions in their clinical management still lack clear answers. This thesis presents four studies examining surgical management and postoperative surveillance in these tumours. 

In Paper I, an international multicentre retrospective cohort of 278 patients with completely resected 1-2 cm aNETs was analyzed. Histopathological risk factors did not identify patients at risk of nodal metastases, and nodal involvement did not affect overall survival. Complete resection (R0) was the only variable associated with nodal status, and survival was similar between patients treated with appendectomy alone and those who underwent completion right hemicolectomy. Distant metastases arising from the primary aNET were confirmed in only four cases, with no tumor-related mortality. The data argue against completion right hemicolectomy in 1-2 cm aNETs.

Paper II compared hand-assisted laparoscopic surgery (HALS) with open laparotomy in 97 SI-NET patients. R0 resection rates, operative time, and hospital stay were comparable between techniques, while epidural analgesia use was markedly lower in the HALS group. HALS was found to be a feasible and oncologically safe approach.

Paper III followed asymptomatic patients with stage IV SI-NETs managed without prophylactic surgery of the primary tumours and mesenteric metastases. Over ten years, only 9% developed symptoms requiring surgical intervention, and mesenteric metastasis volumes remained largely stable. Routine prophylactic resection does not appear justified in this patient group.

Paper IV examined the prognostic role of 68Ga-DOTATOC-PET/CT in 244 patients with radically resected stage I-III SI-NETs. Preoperative imaging modality was not associated with relapse risk. Having at least one negative postoperative PET/CT, however, was strongly associated with better relapse-free survival, five-year RFS 82% versus 61% and ten-year RFS 61% versus 26%, after adjustment for relevant covariates. The results support a role for postoperative 68Ga-DOTATOC-PET/CT as a clinically meaningful surveillance tool. 

In conclusion, these findings contribute evidence that may refine current surgical practice and surveillance strategies for SI-NETs and aNETs.