PCV chemotherapy for oligodendroglioma: response analyzed on T2 Weighted-MRI

Objective: Because oligodendroglioma are infiltrative tumors, the Mac Donald's response criteria, usually used for solid and contrast-enhanced tumors, seem not to be adapted. To precise more relevant radiological criteria, the radio-logical response of oligodendroglioma to PCV chemotherapy was evaluated on T2 weighted-MRI sequences only. Methods: 25 patients with oligodendroglioma grade A or B were retrospectively analyzed. They were treated with up to six cycles of PCV standard regimen. Tumor size was calculated before and at the end of the treatment, on T2 weighted-MRI, by two methods: volumetric reconstruction (method 1) and maximal cross-sectional area (method 2). Responses were defined according to new criteria on T2 weighted-MRI. Results: According to these criteria and with the method 1, 7 of 25 patients (28%) had a partial response to the PCV, 14 patients (56%) had stabilized disease, and 4 patients (16%) had progressive disease. With the method 2, 6 had partial response (24%), 18 had stabilized disease (72%) and 1 had progressive disease. Conclusion: Response rate to PCV chemotherapy in this study was lower than response observed in the literature. Because of the infiltrative feature of oligodendroglioma, we think that the radiological response of these tumors should be evaluated on T2 weighted-MRI. The two methods of tumor size estimation used in this study were almost equivalent. Then, the maximal cross-sectional area measurement, more practical, could be retained.