Objective: Intratumor heterogeneity is of great importance in many clinical aspects of glioma biology, including tumor grading, therapeutic response, and recurrence. Modifications in the genetic features of a specific primary tumor recurring after chemo- and radiotherapy are poorly understood. We report a recurrent glioblastoma case exhibiting loss of heterozygosity (LOH) on chromosome 10q, while the primary tumor exhibited heterogeneity in the LOH status of 1p, 19q, and 10q. To determine the relationship between such modifications and heterogeneous chemosensitivity, primary cultured cells heterogeneously showing 1p/19q/10q losses were established from a surgical specimen of oligoastrocytoma and were treated with chemotherapeutic agents.
Clinical presentation: A 46-year-old woman with a 1-month history of headache and visual disturbances presented to our institution.
Intervention: A right temporoparietal craniotomy and gross total resection were performed. The pathological diagnosis was glioblastoma multiforme with oligodendroglial components. Whereas LOH on 10q was identified at all tumor sites, only the oligodendroglial components exhibited LOH on 1p and 19q. The tumor recurred 6 months after postoperative chemotherapy using interferon-beta and ranimustine, as well as a course of fractionated external-beam radiotherapy (total dose, 60 Gy). Gene analysis revealed no 1p/19q allelic losses but only 10q LOH.
Conclusion: Intratumor heterogeneity might be explained by the presence of more than one subclone in the primary tumor. Here, the tumor cells exhibiting 1p/19q LOH with high chemosensitivity might have been killed by the adjuvant therapy and those exhibiting 10q LOH with chemoresistance recurred. This study and our preliminary laboratory findings might suggest an approach to brain tumor physiology, diagnosis, and therapy.