Increase of pseudoprogression and other treatment related effects in low-grade glioma patients treated with proton radiation and temozolomide
Concurrent radiotherapy and temozolomide (TMZ) is associated with radiographic pseudoprogression (PsP) in glioblastoma. The occurrence of PsP and other treatment effects is less well understood in low-grade gliomas (LGG). The purpose of this study is to evaluate whether the addition of TMZ to radiotherapy increases the incidence of PsP in adults with LGG treated with proton radiotherapy (PRT).
Chart review and volumetric MRI-analysis was performed on radiotherapy-naive adults with WHO grade II or IDH mutant WHO grade III gliomas treated with PRT between 2005 and 2015. Progression was defined by histology, new chemotherapy initiation, or progressive increase in lesion volume beyond 40% from baseline. Post treatment related effects (PTRE) were defined as new/increased T2/FLAIR or abnormal enhancement which eventually resolved or stabilized without evidence of progression for a period of 6–12 months. PsP was defined as the subset of PRTE suspicious for progression or volumetrically increased at least 40% from baseline. Pearson’s chi-squared test and Cox-proportional hazards models were used for statistical analysis.
There were 119 patients meeting inclusion criteria. There was an increased risk of PsP following PRT + TMZ versus PRT-alone (HR = 2.2, p = 0.006, on Cox univariate analysis). Presence of PsP was associated with improved OS (p = 0.02 with PsP as time-varying covariate).
TMZ use, when added to PRT, was associated with increased PsP in patients with LGG; however, patients with PsP tended to achieve longer survival.
KeywordsLow-grade gliomas Proton radiotherapy Pseudoprogression Toxicity Radiation necrosis
Compliance with ethical standards
None of the authors have relevant disclosures.
- 33.Motegi H, Kamoshima Y, Terasaka S, Kobayashi H, Yamaguchi S, Tanino M et al (2013) IDH1 mutation as a potential novel biomarker for distinguishing pseudoprogression from true progression in patients with glioblastoma treated with temozolomide and radiotherapy. Brain Tumor Pathol 30:67–72CrossRefPubMedGoogle Scholar
- 35.Gunther JR, Sato M, Chintagumpala M, Ketonen L, Jones JY, Allen PK et al (2015) Imaging changes in pediatric intracranial ependymoma patients treated with proton beam radiation therapy compared to intensity modulated radiation therapy. Int J Radiat Oncol Biol Phys 93:54–63CrossRefPubMedGoogle Scholar