Quantitative assessment of 99mtc-depreotide uptake in patients with non-small-cell lung cancer: immunohistochemical correlations

Abstract

Somatostatin receptor (SSTR) scintigraphy with (99m)Tc-depreotide is used for differential diagnosis of solitary pulmonary nodules. The method is based on SSTR expression in cancer tissue. To estimate the expression of SSTRs in non-small-cell lung cancer (NSCLC) in vitro, and to determine the correlation between (99m)Tc-depreotide uptake in vivo and different tumor characteristics determined in vitro, such as tumor grade, and presence of SSTR2, MIB-1, and p53. A total of 127 patients with lung lesions detected on computed tomography (CT) were investigated with SSTR scintigraphy after injection of 740 MBq (99m)Tc-depreotide. This study includes 19 patients with NSCLC with histologically proven diagnosis. The quantitative evaluation of (99m)Tc-depreotide was performed using region-of-interest analysis and includes tumor counts/cm(3), background counts/cm(3), and the ratio between tumor and background counts. 99mTc-depreotide uptake was found in all NSCLC tumors, which expressed SSTR2 defined in vitro by immunochemical methods. SSTR2 expression was negatively correlated to the degree of the tumor's differentiation (P<0.05). 99mTc-depreotide uptake in tumor cells did not correlate with tumor grade, or SSTR2, MIB-1, or p53 expression. There is an expression of SSTRs in NSCLC. The degree of tumor differentiation correlates negatively with SSTR2 measured in vitro and positively with MIB-1 expression in tumor tissue. No correlation was found between (99m)Tc-depreotide uptake and possible prognostic factors such as MIB-1 and p53 expression in tumor cells in NSCLC. Lastly, no correlation was found between (99m)Tc-depreotide uptake and tumor grade or SSTR2 expression.