IL6 and central nervous system cancer: Elevated levels of serum IL‐6 associated with tumor size, tumor stage, or disease progression have been found in many neoplastic diseases, such as gastrointestinal tumors, lung cancer, and malignant melanoma.51 Trikha et al revealed that the serum IL‐6 level correlated with clinical extension of the tumor and with outcomes.52 In our study, we found that an elevated circulating IL‐6 level is significantly associated with an increased risk and a poor prognosis of glioma, probably because it is involved in the occurrence and development of glioma.