Cytogenic investigations in the assessment of response to treatment in neuroblastoma.

In a patient with stage IV disseminated neuroblastoma treated by chemotherapy extensive cytogenetic investigations were performed on the residual primary tumour and bone marrow immediately before myeloablative treatment and autologous marrow rescue. Two abnormal clones both showing lp+, a characteristic abnormality of neuroblastoma, were detected in cells from the residual primary tumour, providing direct evidence of persisting viable tumour. Such investigations should be a routine part of the assessment of response to treatment in patients with neuroblastoma, and could be extended to others in whom "second look" surgery is performed.