Cancer cells metastasize via angiogenesis and are a long-standing therapeutic target in malignant tumors. Vascular endothelial growth factor (VEGF) antibodies have been developed for clinical use, with limited benefits. Therefore, identifying the underlying mechanisms of angiogenesis regarding whether tumor vessels are derived from cancer cells or blood vessels in existence, is highly anticipated. Recently, epidermal growth factor receptor (EGFR) antibodies were utilized to detect cancer cells with somatic mutations of EGFR. The concordance rate is high for detection between immunohistochemical staining and polymerase chain reaction (PCR)-based methods. We hypothesized that endothelial cells exhibiting lymphatic and venous tumor invasiveness will be immunoreactive if new blood vessels are derived from the lung cancer itself, because EGFR mutations occur at a relatively early phase in carcinogenesis. We examined endothelial cells with EGFR mutations exhibiting lymphatic and venous tumor invasiveness using these antibodies. Tumor samples were obtained from 848 consecutive patients with lung cancer. Among 153 of 595 adenocarcinomas with EGFR-sensitive mutations, the number of lymphatic and venous invasive tumors was 35 and 19, respectively. Consequently, 12 available tumor specimens (five specimens for delE746-A750 and seven specimens for L858R) with both factors were evaluated. The main cancer cells were highly immunoreactive; however, no obvious lesions were detected with endothelial cells exhibiting lymphatic or venous invasiveness. Therefore, the angiogenesis of lung cancer seems to utilize blood vessels in existence, rather than create new vessels using signals from carcinogenesis.
Keywords: Angiogenesis; EGFR; lung cancer.