The glycoprotein YKL‐40 is synthesized both by cancer cells and by tumor‐associated macrophages and plays a functional role in tumor progression. Consequently, high serum YKL‐40 levels have been associated with a poor prognosis in patients with several cancer types. However, the role of YKL‐40 has not been established in nonsmall cell lung cancer (NSCLC).

Pretreatment serum levels of YKL‐40 were determined in 189 patients with NSCLC (143 men and 46 women; median age, 62 years;, age range, 41‐76 years). Twelve percent of patients had stage IIIB disease, and 88% had stage IV disease. Ninety‐eight patients received combined gemcitabine and vinorelbine, and 91 received combined gemcitabine, vinorelbine, and cisplatin as first‐line chemotherapy. The median overall survival was 37 weeks.

Patients had a median serum YKL‐40 level of 209 ng/mL (range, 19‐2153 ng/mL). No correlation was observed between overall survival and the type of chemotherapy regimen used, tumor stage, sex, or histologic types. Patients with high serum YKL‐40 levels (greater than the median level for all patients [209 ng/mL]) had a significantly shorter survival than patients with serum YKL‐40 levels below the median (median survival, 32 weeks vs 41 weeks; P = .007). In multivariate analysis, the serum YKL‐40 level, the presence of bone lesions, and the serum lactate dehydrogenase level were independent, statistically significant prognostic factors.

The pretreatment serum YKL‐40 level was identified as a new, independent prognostic biomarker in patients with metastatic NSCLC and may help to determine the individual prognosis of these patients. Cancer 2010. © 2010 American Cancer Society.