Serum YKL-40 and interleukin 6 levels in Hodgkin lymphoma

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.

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.

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 (P(trend), 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 >or=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.

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.