CHI3L1 and small cell lung carcinoma: Human chitinase‐like glycoproteins are expressed in several types of solid tumors including breast, colon, kidney, SCLC, ovarian, prostate, and endometrial cancers as well as malignant melanoma, glioblastoma, and Hodgkin's lymphoma.17, 18 CHI3L1 is a chitinase‐like protein lacking enzymatic properties, and its mechanism of action remains an active area of exploration.