Beschreibung:
<jats:p>There is a growing need for more accurate biomarkers to facilitate the diagnosis and prognosis of patients with grade (G) 3 neuroendocrine carcinomas (NECs). In particular, the discrimination between well-differentiated neuroendocrine carcinomas (WD-NECs) and poorly differentiated neuroendocrine carcinomas (PD-NECs) is still an unmet need. We previously showed that <jats:sup>68</jats:sup>Gallium-(<jats:sup>68</jats:sup>Ga-) PET/CT positivity is a prognostic factor in patients with gastroenteropancreatic (GEP) G3 NECs, correlating with a better outcome in terms of overall survival. Here, we hypothesize that <jats:sup>68</jats:sup>Ga-PET/CT could help to discriminate between WD-NECs and PD-NECs, adding complementary information to that obtained from morphologic and biologic factors. A retrospective, single-institution study was performed on 11 patients with histologically confirmed, measurable G3 large- or small-cell GEP-NECs according to the 2017 WHO classification. The staging procedures included a <jats:sup>68</jats:sup>Ga-PET/CT scan. Results of <jats:sup>68</jats:sup>Ga-PET/CT were correlated in univariate analysis with loss of tissue immunohistochemical expression of DAXX/ATRX or RB1 frequently associated with WD-NECs or PD-NECs, respectively. None of the patients with positive <jats:sup>68</jats:sup>Ga-PET/CT showed loss of RB1 expression, whereas among those (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>6</mml:mn></mml:math>) with negative <jats:sup>68</jats:sup>Ga-PET/CT, 4 showed loss of expression. A trend towards a correlation between loss of RB1 expression and negative <jats:sup>68</jats:sup>Ga-PET/CT was observed. Our preliminary data support the hypothesis that PD-NECs carrying RB1 mutation and loss of its expression may be associated with negative <jats:sup>68</jats:sup>Ga-PET/CT. If confirmed in a larger clinical trial, <jats:sup>68</jats:sup>Ga-PET/CT would help in the stratification of G3 NECs.</jats:p>