SOMATOSTATIN RECEPTOR SCINTIGRAPHY IN SMALL-CELL LUNG-CANCER - RESULTS OF A MULTICENTER STUDY

The aims of this study were to determine the accuracy of somatostatin receptor scintigraphy in the detection of the primary tumor and its me tastases in small-cell lung cancer (SCLC) in a large patient populatio n, and to investigate the course of somatostatin uptake in primary tum ors during therapy. Methods: In a total of 100 patients, 134 examinati ons were performed. Twenty-seven of the patients were examined before and after chemotherapy. Planar whole-body images were acquired 4 hr an d 24 hr after injection of approximately 200 MBq In-111-pentetreotide. SPECT of the thorax was performed after 24 hr. Tumor-to-background (T /B) ratios for the primary tumor were averaged from anterior and poste rior projections. Results: Compared to conventional investigations, so matostatin receptor scintigraphy (SRS) visualized the primary tumor wi th varying degrees of uptake in 96% of the examinations. Regional meta stases and distant metastases were detected in 60% and 45% of the exam inations, respectively. The uptake of the somatostatin analog by the p rimary tumor was significantly lower in the patients examined during c hemotherapy as compared to those examined before treatment (T/B ratio = 1.94 +/- 0.79 versus 2.35 +/- 0.9, p < 0.005). A decrease in T/B rat io was noted in patients with remission at the time of SRS (From 2.40 +/- 1.56 to 1.63 +/- 0.72, p < 0.05). No difference in the pretreatmen t uptake of octreotide by the primary tumor was identified between pat ients with tumor progression and those with partial or complete remiss ion. Conclusion: Somatostatin receptor scintigraphy has a high sensiti vity in the detection of the primary tumor in SCLC but fails in the de tection of metastases. Thus, SRS does not provide useful information f or staging of SCLC. Since somatostatin uptake by the primary tumor is affected by chemotherapy, it may be used to follow up on the course of SCLC.