Radt-33. Prognostic and Predictive Effect of Age in Molecularly-Defined Lower Grade Gliomas: A Report From the Prospective Glioma Research (Progres) Database

PURPOSE Age over 40 years is commonly regarded as a “high risk” feature and potential indication for adjuvant chemoradiotherapy for patients with lower grade glioma in most clinical practice guidelines. However, these recommendations are based on retrospective observations and their subsequent incorporation into legacy clinical trials. It is unclear whether age remains a relevant prognostic factor in the molecular era. METHODS The Prospective Gliomas Research [PROGRES] Database contains individual patient-level data from 11 prospective clinical trials or observational registries, including seven international trials from the RTOG, EORTC, or Alliance cooperative groups. We determined the association of age with progression-free survival (PFS) in low grade or anaplastic glioma, stratified by isocitrate dehydrogenase (IDH1/2) status. We validated our findings in a separate multi-institutional retrospective cohort (Retrospective Glioma Research [REGRES] Database). RESULTS We identified 1,619 and 1,271 eligible patients in the PROGRES and REGRES cohorts, respectively. IDH-wildtype tumors were more common in patients >40 years (38% vs, 5%, odds ratio: 11.3 [95%CI 6.5 – 19.7]). Age was associated with PFS in IDH-wildtype (5-year PFS: 6% vs, 24%, P =.003) but not in IDH-mutant glioma (60% vs, 59%, P = 0.22, P value of interaction <.001). In IDH-wildtype tumors, older age predicted aggressive molecular features, including TERT promoter mutation (65% vs, 28%), EGFR amplification (41% vs, 15%), and chromosome +7/-10 alteration (57% vs, 25%). Age was not predictive of a benefit from chemoradiotherapy versus radiotherapy alone in IDH-mutant glioma. CONCLUSION Older age is a putative surrogate for IDH-wildtype status, but was not an independent predictor of progression in IDH-mutant lower grade glioma and did not predict benefit from chemoradiotherapy. In the absence of additional clinical or molecular risk factors, age alone should not be considered an indication for administration or deferral adjuvant treatment. Practice guidelines should be revised to reflect contemporary prognostic factors in the molecular era.