As shown in Figure 1, the mean level of YKL-40 in the pre-chemotherapy serum from SCLC patients (n = 120) was (72.06±27.48 ng/mL), which was significantly higher than the controls (n = 40, 48.41±13.63 ng/mL, p<0.001). Here, CHI3L1 is linked to small cell lung carcinoma.