In the 44 patients with DLBCL who achieved response (PR/CR) after chemotherapy treatment, initial levels of cystatin C were significantly lower (median: 5.456; range: 2.49–15.17 ng/mL) compared with the non-responders (median: 7.037; range: 3.72–10.81 ng/mL; p < 0.001). The gene discussed is CST3; the disease is diffuse large B-cell lymphoma.