99Tcm-flepreotide somatostatin receptor imaging in diagnosis of lung cancer

Objective The high expression of somatostatin receptor in various tumor cells provides the molecular basis for using radiolabeled somatostatin analogs as tumor tracers. Research of somatostatin analogs scintigraphy in both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) have also been reported. The purpose of this study was to investigate the clinical efficacy of 99Tcm-depreotide, a new somatostatin analog, in the diagnosis of lung cancer. Methods The subjects included 52 consecutive patients, with 8 SCLC, 38 NSCLC and 6 benign lung lesions. Histopathological results were obtained in all cases. Planar images of neck and chest were obtained at 4-6 h after injection of 99Tcm-depreotide [(740±60) MBq] and then chest SPECT was performed. The radioactivity ratio of tumor to normal tissue (T/N) was calculated and used as semi-quantitative evaluation. All scintigraphically detected lesions were compared with the findings of other imaging modalities and histopathologieal results. The data were statistically analyzed with SPSS 11.5. Results The sensitivity, specificity and accuracy for 99Tcm-depreotide imaging in differentiating malignant from benign lesions were 93.5% (43/46), 5/6 and 92.3% (48/52). Three false negative cases included two squamons cell carcinomas and one adenocarcinoama. One false positive case was an inflammatory pseudotumor. The T/N ratio in SCLC was significantly higher than that in NSCLC (1.948±0.282 vs 1.280± 0.160, t=0.130, P<0.05). Conclusion With the effectiveness, availability and low cost, 99Tcm-depreotide scintigraphy may be a promising imaging method for detection of both SCLC and NSCLC. Key words: Lung neoplasms;  Receptors, somatostatin;  Tomography, emission-computed, single-photo;  Depreotide