Evaluation of serum neural cell adhesion molecule as a prognostic marker in multiple myeloma

Serum neural cell adhesion molecule (NCAM), a possible prognostic marker for multiple myeloma (MM), was determined by means of an enzyme immunoassay, which showed good linearity and high precision. In 95% of healthy controls (n = 70), NCAM values were below 18.7 U/mL. In patients with monoclorlal gammopathies of undetermined significance (MGUS) (n = 31) or polyclonal gammopathies (n = 53) the cut off was 23.1 U/mL. MM in active stage (n = 52) showed significantly higher NCAM levels (p < 0.001) than in asymptomatic stage (n = 44). In active myeloma the sensitivity of serum markers were found to be: NCAM 40%, beta 2-microglobulin beta 2-M) 52% and serum thymidine-kinase (S-TK) 41% (cut off defined on MGUS). The combined sensitivities ranged between 55 and 60% (NCAM+ beta 2-M, beta 2-M+S-TK, NCAM+S-TK). No correlation with beta 2-M or S-TK could be demonstrated. However, NCAM values were correlated with the concentration of monoclonal immunoglobulin (IgG-paraprotein: r = 0.45; IgA-paraprotein: r = 0.58). In the follow-up of patients with myeloma, NCAM values decreased in response to chemotherapy and were low in smouldering myeloma. But in three patients with progression NCAM did not reflect the tumor activity. At the time of censor, 80% of patients (n = 80) with a pre-treatment NCAM of < 18.5 U/mL and 61% of patients with a NCAM of > 18.5 U/mL were still alive. NCAM showed a low prognostic significance (log-rank: p < 0.07). Seven of ten myeloma patients with CD56 expression on plasma cell surface, which was examined by flow cytometry, displayed a high concentration of NCAM in serum. All other non-Hodgkin's lymphomas (21 immunocytoma, 27 chronic lymphocytic leukemia, 16 centrocytic/centroblastic-centrocytic lymphoma, 24 high-grade lymphoma) had low NCAM concentrations in serum and did not significantly vary in follow-up. In conclusion, serum NCAM could be a marker for the staging and monitoring of MM. However, it seems, that NCAM did not provide additional prognostic information relating to beta 2-M, S-TK or paraprotein.