Scintigraphic imaging of small-cell lung cancer with [ In]pentetreotide, a radiolabelled somatostatin analogue

Recent work suggests that between 50 and 75% of small-cell lung cancer (SCLC) tumours have specific high-affinity binding sites for somatostatin. This study evaluated the potential role of the radiolabelled somatostatin analogue, [111In]pentetreotide, in the detection and staging of SCLC in patients prior to and after chemotherapy using scintigraphic imaging techniques. Thirteen patients were studied prior to chemotherapy. Following standard staging six patients had limited stage disease and seven extensive disease. [111In]pentetreotide imaging led to the detection of all primary sites of disease, including a primary site of disease not detectable with chest radiograph or computerised tomography (CT) of the thorax. Five of ten metastatic sites detected by standard staging were also imaged. Furthermore, a cerebellar metastasis was detected in a patient thought to have disease confined to the right hemithorax. This was subsequently confirmed with a CT brain scan. Following chemotherapy [111In]pentetreotide imaging detected residual intrathoracic disease in two of three patients with complete remissions by standard staging and in two patients who had had a partial response to chemotherapy. These results suggest that [111In]pentetreotide imaging may have a role to play in the clinical evaluation of patients with SCLC. Specifically, this technique may be of particular value in detecting residual intrathoracic disease in patients thought to be in complete remission by conventional staging methods.