There was no significant difference in radiotracer uptake between primary lesions, lymph node metastases, pleural metastases, hepatic metastases, bone metastases and adrenal metastases (P > 0.05), indicating uniform and high CXCR4 density on the primary and metastases in SCLC (Figure 5I). This evidence concerns the gene CXCR4 and metastatic malignant neoplasm in the lymph nodes.