Somatostatin receptor scintigraphy in the follow up of neuroendocrine neoplasms of appendix

Abstract

BACKGROUND Neuroendocrine tumors of appendix (ANETs) known as carcinoids, are rare endocrine neoplasms originated from enterochromaffin cells of gastrointestinal tract. ANETs are the third most frequent (16.7%) gastrointestinal neuroendocrine tumors, with the incidence of 0.08-0.2 cases/100000 during one year. Incidental ANETs occur in 0.2%-0.7% of emergency surgical resections because of suspected appendicitis which is usually the first manifestation of ANET. Although there are a lot of papers about application of somatostatin receptor scintigraphy in gastrointestinal neuroendocrine tumors, there are very rare sporadic cases described about ANETs particularly. AIM To establish the role of somatostatin receptor scintigraphy (SRS) in the management of patients with neuroendocrine tumors of appendix (ANET). METHODS The total of 35 patients was investigated, 23 females and 12 males, average age (43.7 ± 17.3 years). All patients had histological diagnosis of ANET (34 carcinoids of appendix and one tubular carcinoid). Majority of tumors have been found incidentally during surgery of: Acute appendicitis ( n = 15), perforated appendicitis ( n = 2), ileus ( n = 3), hysterectomy ( n = 3), ruptured ovarian cyst ( n = 2), caecal volvulus ( n = 1), while 9 patients had diagnosis of appendiceal tumor before the surgery. Seventeen patients had tumor grade (G) G1, 12 G2 and 6 G3. The right hemicolectomy was performed in 13, while the rest of the patients had appendectomy only. SRS was done early (2 h) and late (24 h) after i.v . application of 740 MBq technetium-99m ethylenediamine-N, N'-diacetic acid Hydrazinonicotinyl-Tyr3-Octreotide (technetium-99m-Tektrotyd, Polatom, Poland). SRS was performed for restaging in all the patients after surgery. RESULTS There were 12 true positive (TP), 19 true negative, 3 false positive and 1 false negative SRS result. Sensitivity of the method was 92.31%, specificity was 86.36%, positive predictive value was 80.00%, negative predictive value was 95.00% and accuracy 88.57%. Receiver operating characteristics analysis showed that SRS scintigraphy is a good test for detection TP cases [area under the curve of 0.850, 95% confidence interval (CI): 0.710-0.990, P < 001]. Single photon emission computed tomography contributed diagnosis in 7 TP findings. In 10 patients Krenning score was 4 and in 2 was 3. In 8 patients SRS significantly changed the management of the patients (in two surgery was repeated, in 4 somatostatin analogues and in two peptide receptor radionuclide therapy). Median progression-free survival in SRS positive patients was 52 months (95%CI: 39.7-117.3 mo) while in SRS negative patients it was 60 months (95%CI: 42.8-77.1 mo), without statistically significant differe...

Management of incidentally discovered appendiceal neuroendocrine tumors after an appendicectomy

“…There are a multitude of articles on the applications of SRS in GEP-NETs, however, only sporadic cases of aNET have been described in this body of literature[ 22 , 23 ]. ⁠ SRS using either indium-111 or technetium-99m (including single photon emission CT) or a PET scan using gallium-68-labeled somatostatin analogs (SSAs) in combination with a CT scan can be considered in cases in which curative resection is not completely assured or when distant metastasis is suspected[ 24 ].…”

“…⁠ SRS using either indium-111 or technetium-99m (including single photon emission CT) or a PET scan using gallium-68-labeled somatostatin analogs (SSAs) in combination with a CT scan can be considered in cases in which curative resection is not completely assured or when distant metastasis is suspected[ 24 ]. In these cases, published studies suggest that SRS is useful for detecting residual disease[ 23 , 25 ] and that SRS results could modify management in 20% to 25% of patients[ 23 , 26 ], mainly for those with high proliferative activity.…”