Correlation and Comparison of Somatostatin Receptor Type 2 Immunohistochemical Scoring Systems with 68Ga-DOTATATE Positron Emission Tomography/Computed Tomography Imaging in Gastroenteropancreatic Neuroendocrine Neoplasms.

The overexpression of somatostatin receptor type 2 (SSTR2) is a unique characteristic of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs), which establishes the basis for both diagnosis and therapy. The SSTR status can be evaluated by immunohistochemical staining (IHC) and 68Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) imaging. This study attempted to determine the relationship between IHC and 68Ga-DOTATATE PET/CT imaging and to explore the optimal cutoff value for SSTR IHC reading. A total of 100 GEP-NENs with SSTR PET/CT and pathological data were retrospectively analyzed, which consisted of neuroendocrine tumor (NET) G1 (n = 9), NET G2 (n = 64), NET G3 (n = 13), neuroendocrine carcinoma ( n = 10), and mixed neuroendocrine-non-NENs ( n = 4). SSTR2-IHC results were interpreted by 4 well-established semiquantitative scoring systems, including human epidermal growth factor receptor 2 (HER2) score, Volante score, H score, and immunoreactive score. In the homogeneous SSTR2 expression group (accounting for 57% of all cases), the 4 scoring systems were highly concordant with each other (Kendall's Tau-b coefficient range: 0.80-0.96, p < 0.001) and also highly correlated with the 68Ga-DOTATATE PET/CT imaging results (Spearman's rank correlation coefficients: 0.71, 0.86, 0.80, and 0.71, p < 0.001). In the heterogeneous group (43%), the 4 scoring systems revealed a lower level of concordance (the Kendall Tau-b coefficient range: 0.40-0.75, p < 0.01), and the correlation with 68Ga-DOTATATE PET/CT imaging was also lower, albeit statistically significant (Spearman's rank correlation coefficients: 0.53, 0.38, 0.36, and 0.33, p < 0.05). Heterogeneous SSTR2 expression was mainly observed in the HER2 2+ cases, for which the combination with H score could help identify positive cases with increased sensitivity and specificity. The highest sensitivity and specificity of H scores in predicting the imaging results were achieved at 86.10 and 89.30% when defining the cutoff value as 160, indicating that 80% of the tumor cells were moderately positive or 55% were strongly positive. SSTR2 IHC was found to predict 68Ga-DOTATATE PET/CT imaging accurately, especially in the homogeneous expression group. According to the positive 68Ga-DOTATATE PET/CT outcomes, 80% of the tumor cells moderately positive or 55% strongly positive was the cutoff values for SSTR2-IHC reading.

Yu J ，Cao F ，Zhao X ，Xie Q ，Lu M ，Li J ，Yang Z ，Sun Y ... -  《-》

Correlation of somatostatin receptor PET/CT imaging features and immunohistochemistry in neuroendocrine tumors of the lung: a retrospective observational study.

To correlate somatostatin receptor (SSTR) and proliferative activity profile (SSTR2, SSTR5, Ki-67) at immunohistochemistry (IHC) with SSTR-PET/CT imaging features in a retrospective series of lung neuroendocrine tumors (NET). Proliferative activity by Ki-67 and 18F-FDG-PET/CT parameters (when available) were also correlated. Among 551 patients who underwent SSTR-PET/CT with 68Ga-DOTA-somatostatin analogs (SSA) between July 2011 and March 2020 for lung neuroendocrine neoplasms, 32 patients with a confirmed diagnosis of NET were included. For 14 of them, 18F-FDG-PET/CT was available. PET/CT images were reviewed by qualitative and semi-quantitative analyses. Immunohistochemistry for SSTR2, SSTR5, and Ki-67 was assessed. Inferential analysis was performed including kappa statistics and Spearman's rank correlation test. Definitive diagnosis consisted of 26 typical carcinoids-G1 and six atypical carcinoids-G2. Positive SSTR2-IHC was found in 62.5% of samples while SSTR5-IHC positivity was 19.4%. A correlation between SSTR2-IHC and SSTR-PET/CT was found in 24/32 cases (75.0%, p = 0.003): 20 were concordantly positive, 4 concordantly negative. For positive IHC, 100% concordance with SSTR-PET/CT (both positive) was observed, while for negative IHC concordance (both negative) was 33.3%. In 8 cases, IHC was negative while SSTR-PET/CT was positive, even though with low-grade uptake in all but one. A significant correlation between SUVmax values at SSTR-PET/CT and the SSTR2-IHC scores was found, with low SUVmax values corresponding to negative IHC and higher SUVmax values to positive IHC (p = 0.002). This retrospective study showed an overall good agreement between SSTR2-IHC and tumor uptake at SSTR-PET/CT in lung NETs. SSTR-PET/CT SUVmax values can be used as a parameter of SSTR2 density. Within the limits imposed by the relatively small cohort, our data suggest that SSTR2-IHC may surrogate SSTR-PET/CT in selected lung NET patients for clinical decision making when SSTR-PET/CT is not available.

Rufini V ，Lorusso M ，Inzani F ，Pasciuto T ，Triumbari EKA ，Grillo LR ，Locco F ，Margaritora S ，Pescarmona E ，Rindi G ... -  《-》

The Correlation Between [(68)Ga]DOTATATE PET/CT and Cell Proliferation in Patients With GEP-NENs.

Yu J ，Li N ，Li J ，Lu M ，Leal JP ，Tan H ，Su H ，Fan Y ，Zhang Y ，Zhao W ，Zhu H ，Pomper MG ，Zhou Y ，Yang Z ... -  《-》

Performance of 177Lu-DOTATATE-based peptide receptor radionuclide therapy in metastatic gastroenteropancreatic neuroendocrine tumor: a multiparametric response evaluation correlating with primary tumor site, tumor proliferation index, and dual tracer imag

Thapa P ，Ranade R ，Ostwal V ，Shrikhande SV ，Goel M ，Basu S ... -  《-》

Comparison of 68Ga-DOTANOC and 68Ga-DOTATATE PET/CT within patients with gastroenteropancreatic neuroendocrine tumors.

Wild D ，Bomanji JB ，Benkert P ，Maecke H ，Ell PJ ，Reubi JC ，Caplin ME ... -  《-》