Serum YKL-40 and interleukin 6 levels in Hodgkin lymphoma

Abstract

Purpose: Serum levels of the inflammatory markers YKL-40 and interleukin 6(IL-6) are increased in many conditions, including cancers. We examined serum YKL-40 and IL-6 levels in patients with Hodgkin lymphoma, a tumor with strong immunologic reaction to relatively few tumor cells, especially in nodular sclerosis Hodgkin lymphoma. Experimental Design: We analyzed Danish and Swedish patients with incident Hodgkin lymphoma (N = 470) and population controls from Denmark (n = 245 for YKL-40; n = 348 for IL-6). Serum YKL-40 and IL-6 levels were determined by ELISA, and log-transformed data were analyzed by linear regression, adjusting for age and sex. Results: Serum levels of YKL-40 and IL-6 increased in Hodgkin lymphoma patients compared with controls (YKL-40, 3.6-fold; IL-6, 8.3-fold; both, P < 0.0001). In pretreatment samples from pretreatment Hodgkin lymphoma patients (n = 176), levels were correlated with more advanced stages (Ptrend, 0.0001 for YKL-40 and 0.013 for IL-6) and in those with B symptoms; however, levels were similar in nodular sclerosis and mixed cellularity subtypes, by EBV status, and in younger (<45 years old) and older patients. Patients tested soon after treatment onset had significantly lower levels than pretreatment patients; however, even ≥6 months after treatment onset, serum YKL-40 and IL-6 levels remained significantly increased compared with controls. In patients who died (n = 12), pretreatment levels for YKL-40 and IL-6 were higher than in survivors, although not statistically significantly. Conclusions: Serum YKL-40 and IL-6 levels were increased in untreated Hodgkin lymphoma patients and those with more advanced stages but did not differ significantly by Hodgkin lymphoma histology. Following treatment, serum levels were significantly lower. ©2008 American Association for Cancer Research.