ACTR-03. INDUCING FACTORS OF MALIGNANT RECURRENCE IN LOW-GRADE GLIOMA

Abstract

Low-grade glioma patients have relatively long life expectancy for gliomas, but once they recur in malign, their prognosis can be poor. We analyzed factors corresponding to malignant recurrence by uni- and multi-variate analysis applying their treatment backgrounds. SUBJECTS: 261 newly diagnosed WHO grade 2 adults gliomas in 2004 to 2014. Malignant recurrence was determined by pathological diagnosis if the patient had a surgery (69% of the recurrent patients), otherwise contrast T1WI or 11C- methionine PET images if the patient was unable to undergo any surgery or biopsy.

RESULTS

Age average 41 years old, the 10-year survival rate in all patients was 75%, and the mean of progression-free survival time was 7.8 years. Relapse event occurred in 115 cases (44%), and 67 % of them developed malignant glioma sometime. The 10-year survival rate for the patients who relapsed in malign was 37%, on the contrary, the patients who had recurrence but staying in low grade was 71% (p=0.0389). When they were categorized by 1p19q deletion and IDH1 mutation status, IDH wild type diffuse astrocytoma patients had significantly developed malignant glioma compared to oligodendroglioma and IDH mutant type diffuse astrocytoma (p<0.0001). The factors related to malignant progression were extracted as; recurrence in 2 years, 6% and over in MIB-1 index, no intervention longer than 18 months since the disease revealed, 1p19q non-co-deletion, less than 90% of tumor resection rate, and IDH wild type. In the 1p19q non-deletion patients, who were provisionally defined as diffuse astrocytoma patients here, the factors were resection rate, MIB-1 index, and duration between discovered the disease and the first surgery, but not the IDH mutant status (p＜0.0001, p=0.0015, p=0.0478 respectively).

CONCLUSION

Recurrence in malign form low-grade glioma can be avoided by early intervention in 18 months from diagnosis and resection over 90% of volume of the tumor.