Low-molecular weight caldesmon as a potential serum marker for glioma.

PURPOSE: Testing the feasibility of using the serum low-molecular weight caldesmon (l-CaD) level as a serum marker for the presence of glioma. EXPERIMENTAL DESIGN: Within a total of 230 serum samples, the l-CaD level was measured in healthy volunteers (30), patients with gliomas (57), nonglial intracranial tumors (107), and nontumor neurologic diseases (36) by ELISA. The specificity of the assay was monitored by combination of immunoprecipitation and immunoblotting. RESULTS: The serum level of l-CaD is significantly higher in the group of glioma patients as compared with any of the other groups (P < 0.001). The cutoff value of 45 yields optimal sensitivity and specificity of the assay (91% and 84%, respectively; area under the curve score = 0.91). The specificity of ELISA was confirmed by the immunoprecipitation/immunoblotting control experiments. There were no significant differences in serum l-CaD levels between patients with low- or high-grade gliomas. CONCLUSIONS: The serum l-CaD level as determined by ELISA is a good discriminator between glioma patients versus patients with other intracranial tumors, other neurologic diseases, and healthy people. Prospective studies are required to test the contribution of the assay in making the diagnosis of glioma, or its feasibility for monitoring the tumor during treatment.