Prognostic implications of YKL-40 overexpression in breast cancer

Abstract

20115 Background: YKL-40 has been implicated as a connective tissue growth factor and a migratory factor for endothelial cells. Elevated serum levels of YKL-40 have been found to correlate with worse survival in a variety of malignancies including breast cancer. We wished to determine if tumor overexpression of this protein also had prognostic implications in breast cancer. Methods: A prospectively collected database of breast cancer patients treated at the University Hospital of Newark was used for analysis. Immunohistochemical analysis was performed on 115 patients for whom full clinical information and follow up was available. Specimens were categorized as lacking immunoreactivity (0), having focal sparse immunoreactivity (1), or strong more diffuse immunoreactivity (2). Results: YKL-40 expression was noted in 38 patients (33%). Of these, 24 demonstrated strong (2) immunoreactivity (21%). Strong (2) YKL-40 immunoreactivity significantly correlated with larger tumor size (p < .05). Tumors expressing any level of YKL-40 were also significantly more likely to be estrogen and/or progesterone receptor negative (p < .01). No significant correlation was demonstrated between YKL-40 status and nodal stage. At a mean follow up of 2.3 years, disease-free survival was significantly worse in the subset of patients whose tumors overexpressed any level of YKL-40 compared to the non-expressors (p < .01). In multivariate analysis, YKL-40 status was independent of T-stage and N-stage in predicting disease recurrence. Conclusions: Immunoreactivity for YKL-40 was a significant predictor of breast cancer relapse in this subset of patients. This was independent of T or N-stage and suggests that tumor immunohistochemistry for this protein may be a valuable prognostic marker in breast cancer. No significant financial relationships to disclose.