Relationship of YKL-40 protein expression in pulmonary adenocarcinoma and prognosis.

Abstract

e18129 Background: YKL-40 (CHI3L1) is synthesized both by cancer cells and tumor-associated macrophages and plays a functional role in tumor progression. High YKL-40 serum levels have been associated with poor prognosis in patients with several cancer types including non-small cell lung cancer (NSCLC). YKL-40 protein expression has been investigated by immunhistochemistry in several cancer types but not in NSCLC. The aim of the present investigation was to analyze the expression of YKL-40 of pulmonary adenocarcinoma cells. Methods: YKL-40 protein was assessed by immunhistochemistry using a monoclonal antibody against YKL-40 in primary tumors or lymph node metastases of 83 patients with metastatic adenocarcinoma of the lung who underwent surgery between 1999 and 2002. The immunreactivity was assessed by two independent observers using the immureactive score (IRS) according to Stegner and Remmele. YKL-40 IRS was related to tumor stage, progression-free survival (PFS) and overall survival (OS). Results: In 77 cases (93%), the IRS was positive. In most tissues, the staining intensity of the tumor cells was strong (n = 47, 57%) or moderate (n = 30, 36%). The percentage of positive tumor cells was high; in 66 tissues (80%) > 80% of the tumor cells were positive and in 3 tissues only none or < 10% of the tumor cells were positive. There was no correlation between YKL-40 IRS and tumor stage. For survival analysis, 79 patients were evaluable. Median PFS was 11.7 months (range 10.6-16.7 months) and median OS was 20.3 months (range 16.8-30.8 months). There was no difference in PFS and OS depending on the YKL-40 IRS. Conclusions: In pulmonary adenocarcinomas YKL-40 protein expression was found with a strong staining intensity and a high percentage of positive tumor cells. In contrast to serum YKL-40 levels, YKL-40 expression was not correlated with PFS or OS. This is in accordance with the results of YKL-40 protein expression in breast, ovarian and head and neck cancer. No significant financial relationships to disclose.