Risk Factors for Malignant Transformation of Low Grade Glioma

Publication date: Available online 21 December 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Erin S. Murphy, Charles M. Leyrer, Michael Parsons, John H. Suh, Samuel T. Chao, Jennifer S. Yu, Rupesh Kotecha, Xuefei Jia, David M. Peereboom, Richard A. Prayson, Glen HJ. Stevens, Gene H. Barnett, Michael A. Vogelbaum, Manmeet S. Ahluwalia
BackgroundThe incidence, risk factors, and outcomes of LGG patients who undergo malignant transformation (MT) in the era of temozolomide (TMZ) are not well known. This study evaluates these factors from a large group of WHO Grade II glioma patients treated at a tertiary care institution.MethodsPatient, tumor, and treatment factors were analyzed from an IRB-approved LGG database. Characteristics were compared using Chi-square and Wilcoxon signed-rank tests. Time-to-event was summarized using proportional hazards models. Univariate and multivariate survival analyses were performed.ResultsFrom a total of 599 patients, 124 underwent MT; 76 (61.3%) were biopsy-proven. MT incidence was 21% and median time to MT 56.4 months. The 5 and 10-year PFS for MT patients was 30.6% ± 4.2% and 4.8 % ± 1.9%, and for non-MT patients was 60% ± 2.4% and 38% ± 2.7%, respectively. The 5 and 10-year OS for MT was 75% ± 4.0% and 46 % ± 5.0% and non-MT patients was 87% ± 1.7% and 78% ± 2.3%, respectively. On MVA, older age (p=0.001), male sex (p=0.004), multiple tumor locations (p=0.004), chemotherapy alone (p=0.012), and extent of resection (p=0.045) remained significant predictors of MT.ConclusionsMT impacts survival. Risk factors include older age, male sex, multiple tumor locations, use of chemotherapy alone, and presence of residual disease. Our findings that initial interventions could impact the rate of MT are provocative, but this data should be validated using data from prospective trials. In addition to improving survival, future therapeutic efforts should focus on preventing MT.

Teaser

The incidence, risk factors, and outcomes of LGG patients who undergo malignant transformation in the era of temozolomide are not well known. This study evaluates these factors from a large group of WHO Grade II glioma patients treated at our tertiary care institution. We found that older age, male sex, multiple tumor locations, chemotherapy alone, and extent of resection were significant predictors of malignant transformation.


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