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Top Line: Many of us use concurrent temozolomide (TMZ) and radiation to treat high-risk, low-grade glioma.
The Study: But why? The data for adding chemo to radiation mainly comes from RTOG 9802 where adding sequential (not concurrent) PCV after 54 Gy significantly improved overall survival. But most will side with the phase 2 data from RTOG 0424 and use the concurrent/adjuvant TMZ approach, so here we have its long-term results. To be eligible, patients had to have 3 of the following risk factors (i.e. had to be high-risk per EORTC): age 40+, ≥6 cm tumor, bi-hemspheric tumor, astrocytoma histology, or a moderate to severe neurological symptom at presentation. The target was the post-op cavity, residual tumor, and post-op FLAIR plus a 1.5 cm CTV and 5 mm PTV margin. This received 1.8 Gy x 30 = 54 Gy with concurrent TMZ followed by twelve cycles of adjuvant TMZ. What’s new here? Median overall survival was 8.2 years and median progression-free survival was 4.5 years. At 5 years, progression-free survival (PFS) was 47% and OS was 61%. At 10 years, PFS was 26% and OS was 37%. By comparison, in 9802, the PFS was 51% and OS 60% 10-years out from radiation → PCV, but criteria for “high-risk” were looser including anyone with age of 40+ alone. On the other hand, outcomes were notably better than historically with radiation alone. Importantly, molecular subset analysis of 0424 is ongoing.
TBL: Long-term results support TMZ with radiation for high-risk low-grade glioma. | Fisher, Int J Radiat Oncol Biol Phys 2020