Detection of neuroblastoma cells in blood

Tumor surveillance tests are used to detect relapse and to guide the clinician in making therapeutic changes. Identification of relapse early in the course of disease may improve long-term survival. For patients with neuroblastoma, current conventional surveillance methods include radiologic testing, bone marrow analysis, physical examination, and measurement of urinary catecholamine metabolites. Immunocytologic analysis of blood for the detection of circulating tumor cells is a highly specific and sensitive method, which may prove useful in monitoring patients with neuroblastoma. In our study, circulating tumor cells were detected in seven of 10 patients with known disseminated disease at diagnosis and in six of 13 patients during therapy. In some patients, as few as two tumor cells were identified among 100,000 normal hematopoietic cells. The presence or absence of circulating neuroblasts in the 13 patients evaluated during therapy was significantly correlated with tumor relapse (P = .002). We conclude that immunocytologic analysis of blood is a sensitive method for the detection of circulating neuroblasts. We recommend that this technique be used in conjunction with other conventional methods for improved tumor detection and subsequent monitoring of neuroblastoma patients.