VEGFA and lung carcinoma: Furthermore, VEGF has a direct effect on osteoblasts and osteoclasts.[2] As stated by Armstrong et al,[6] in lung carcinoma, there may be some degree of shunting, secondary to local tissue destruction; however, the main source of growth factors are the malignant cells, and this hypothesis is supported by the resolution of the clubbing after tumor resection in most of the patients.