The prognostic influence of the proliferative discordance in metastatic pancreatic neuroendocrine carcinoma revealed by peptide receptor radionuclide therapy: Case report and review of literature.

RATIONALE

Pancreatic neuroendocrine tumors (pNET) are rare slowly growing tumors with a high metastatic potential. Peptide receptor radionuclide therapy (PRRT) with radiolabeled analogues has been developed as a new tool for the management of metastatic well-differentiated (grade 1 and 2) neuroendocrine tumors expressing somatostatin receptor (SSTR2). Chemotherapy is the mainstay in the management of grade 3 (G3) unresectable pancreatic neuroendocrine carcinoma (pNEC). To date, no study has evaluated the efficacy of PRRT in such tumors.

DIAGNOSES AND INTERVENTIONS

We describe a case of a progressive G3 pNEC with huge liver metastases successfully treated with PRRT (Lu DOTATATE).

OUTCOMES

Complete remission was obtained for 3 years. Indeed, the mitotic index was low (as G2 tumors) but with a very high Ki-67 index (45%-70%). Such discordance between the proliferative markers should consider the use of PRRT before chemotherapy in unresectable metastatic G3 tumors expressing SSTR2.

LESSONS

This case supports the hypotheses highlighting the heterogeneity of G3 pNEC. The latter should be subdivided into 2 distinct categories: proliferation-discordant (well differentiated) and concordant (poorly differentiated) NEC. PRRT could be suggested for the former group before the conventional chemotherapy.