Serum levels of monocyte-derived cytokines, such as interleukin (IL)-6, granulocyte colony-stimulating factor (G-CSF), and granulocyte–macrophage colony-stimulating factor (GM-CSF), are also increased in lung cancer patients, particularly, G-CSF levels are positively correlated with lung cancer severity [13]. This evidence concerns the gene IL6 and lung cancer.