P09.40 Clinical behavior of the glioblastomas showing a radiation necrosis and tumor mixed pathology in recurrence or progression

摘要

The current standard treatment for newly diagnosed glioblastoma patients is surgical resection followed by concurrent chemoradiotherapy with temozolomide. When progression is suspected during the treatment protocol, surgical resection is considered. Focal tumor cells can be found within extensive radiation necrosis specimens, and whether to categorize this finding as tumor progression or radiation necrosis is debatable. From June 2006 to June 2016, 115 patients were diagnosed as glioblastoma and 93 of them completed their concurrent chemoradiotherapy. During follow up, 31 patients underwent surgery due to radiologic progression. While 23 patients were diagnosed as recurrent glioblastoma, 8 patients’ specimen showed extensive radiation necrosis with a few tumor cells. Four patients who showed 1p19q codeletion positive and 4 patients who did not have available study results were excluded from the study according to the recent change in CNS tumor diagnosis from the 2016 WHO classification. Among the 6 patients in the mixed pathology group, 5 of them were discontinued from the primary treatment. Overall survival (OS) and survival after radiologic progression (SARP) was measured, and analyzed using the Kaplan-Meier method. Comparing the recurrence group and the mixed pathology group, MGMT methylation PCR results showed positive findings in 6/17 (35.3%) and 4/6 (66.7%), respectively. Although this finding suggests superior outcome on the mixed pathology group, the mean OS was 25.86 (SD 3.15, 95% CI 19.70-32.02) and 25.20 (SD 5.34, 95% CI 14.74-35.66) for recurrence and mixed pathology groups, respectively, with no statistical significance (p=0.875). The mean SARP was 9.63 (SD 1.06, 95% CI 7.56-11.7) and 13.20 (SD 2.05, 95% CI 9.19-17.22) for recurrence and mixed pathology groups. The survival curve showed superior outcome in the mixed pathology group, but failed to obtain statistical significance (p=0.110). The tendency of longer SARP in the mixed pathology group suggests the possibility of a better prognosis group within the previously known recurrence cases. The decision of treatment failure may have been premature in selected patients, and further study is warranted in order to define the exact patient group.