Clonal evolution in a human neuroblastoma

Tumor samples, obtained from a single patient at two points in his illness, have enabled us to study clonal evolution in a neuroblastoma. Cells from the primary tumor demonstrated considerable heterogeneity in terms of chromosome number; cells from 4 subsequent metastases were all nearly diploid; and cells from a tumor produced in a mouse by the injection of cells from the primary tumor were hypotriploid in modal number. All of the tumor samples contained the same marker chromosome rearrangements, indicating their origin from a common precursor. Each of the cell lines analyzed (including those from the patient's metastases, those from the tumor in a mouse, and those from the primary tumor after 11 months in continuous culture) also contained different and distinguishing chromosome abnormalities. The differences in karyotype among these tumor samples and cell lines presumably reflect the different selection pressures at work in each instance.