Roxanne C.S. van Adrichem1, Kimberly Kamp1, Carolien H. M. van Deurzen2, Katharina Biermann2, Richard A. Feelders1, Gaston J H Franssen3, Dik J. Kwekkeboom4, Leo J. Hofland1, Wouter W. de Herder1
1Sector of Endocrinology, Department of Internal Medicine, and Departments of
2Pathology
3Surgery and
4Nuclear Medicine, Erasmus MC, Rotterdam, The Netherlands
Tóm tắt
<b><i>Background and Aims:</i></b> It is unknown whether tumoral somatostatin receptor subtype 2a (sst<sub>2a</sub>) immunohistochemistry (IHC) has additional value compared to somatostatin receptor scintigraphy (SRS) uptake using OctreoScan® in predicting response to peptide receptor radiotherapy using <sup>177</sup>Lu-octreotate (PRRT) in patients with gastroenteropancreatic neuroendocrine tumors (GEP-NETs). The aims of this study were: (1) to establish the percentage of sst<sub>2a</sub> immunopositivity in GEP-NET samples of PRRT-treated patients, (2) to determine the relationship between best GEP-NET response using RECIST 1.0 criteria 1 year after PRRT and tumoral sst<sub>2a</sub> IHC, and (3) to compare characteristics of patients with sst<sub>2a</sub> IHC-negative and -positive tumors. <b><i>Methods:</i></b> All 73 consecutive patients were selected for PRRT based on a positive SRS. Radiological response was scored according to RECIST 1.0 criteria. sst<sub>2a</sub> status was detected on tumor samples by IHC. <b><i>Results:</i></b> In total, 93% of GEP-NET samples showed sst<sub>2a</sub> IHC positivity. No statistically significant relationship was observed between in vitro sst<sub>2a</sub> expression and in vivo best GEP-NET response 1 year after PRRT (p = 0.47). Sex, primary tumor site, disease stage, ENETS TNM classification, Ki-67 index, highest serum chromogranin-A level, and highest neuron-specific enolase level were not significantly different between patients with negative and positive sst<sub>2a</sub> tumoral IHC with the exception of age at diagnosis (p = 0.007). <b><i>Conclusions:</i></b> sst<sub>2a</sub> IHC of tumor samples has no additional value compared to SRS uptake using OctreoScan® in predicting tumor response after PRRT.
