ELISA analysis of serum samples revealed that the protein level of CHI3L1 in patients with lymphoma was significantly greater than that in healthy controls, that the serum CHI3L1 protein level in patients with stage III-IV lymphoma was significantly greater than that in healthy controls, and that the serum CHI3L1 protein level in patients with stage III-IV lymphoma was significantly greater than that in patients with stage I-II lymphoma. The gene discussed is CHI3L1; the disease is lymphoma.