Abstract
Purpose: :
. High circulating levels of interleukin-6 (IL-6), a pro-angiogenic cytokine involved in tumor growth and proliferation, have been associated with poor prognosis in metastatic cutaneous melanoma. We evaluated whether IL-6 concentrations measured in the serum are predictive of outcome in patients with melanoma of the uveal tract.
Methods: :
. We evaluated 770 patients diagnosed with uveal tract melanoma and treated with proton therapy, who had contributed a blood sample at diagnosis or after irradiation. Vital status was ascertained through active follow-up, chart reviews, and a search of the Social Security Death Index. Median follow up among surviving patients was 6.5 years. Il-6 concentrations were measured using commercially available ELISA kits (R&D Systems, Inc., Minneapolis, MN) according to the manufacturer's instructions and intra-assay reliability was assessed in paired samples from sixteen patients (Pearson r=0.952; p<0.001). The association between circulating IL-6 concentrations and risk of melanoma-related mortality was evaluated in multivariate Cox regression models that included terms for tumor size, extrascleral invasion, anterior-most tumor margin and patient age.
Results: :
. Serum concentrations of IL-6 were comparable in patients that developed metastasis (N=121; median: 1.91 pg/ml) and those that remained metastasis-free during the follow-up period (N=649; median: 1.94 pg/ml). Measurements of IL-6 were positively correlated with patient age (Pearson r = 0.22; P<0.001), but were independent of tumor-associated prognostic factors (not shown). Multivariate regression models failed to demonstrate any association of IL-6 with subsequent development of metastasis (P trend = 0.944).
Conclusions: :
. These preliminary results suggest that serum IL-6 is not a useful biomaker of tumor aggressiveness in uveal melanoma.
Keywords: melanoma • cytokines/chemokines • clinical (human) or epidemiologic studies: risk factor assessment