Re-irradiation of recurrent glioblastoma using helical TomoTherapy with simultaneous integrated boost: preliminary considerations of treatment efficacy

Abstract

Although there is still no standard treatment for recurrent glioblastoma multiforme (rGBM), re-irradiation could be a therapeutic option. We retrospectively evaluated the efficacy and safety of re-irradiation using helical TomoTherapy (HT) with a simultaneous integrated boost (SIB) technique in patients with rGBM. 24 patients with rGBM underwent HT-SIB. A total dose of 20 Gy was prescribed to the Flair (fluid-attenuated inversion recovery) planning tumor volume (PTV) and 25 Gy to the PTV-boost (T1 MRI contrast enhanced area) in 5 daily fractions to the isodose of 67% (maximum dose within the PTV-boost was 37.5 Gy). Toxicity was evaluated by converting the 3D-dose distribution to the equivalent dose in 2 Gy fractions on a voxel-by-voxel basis. Median follow-up after re-irradiation was 27.8 months (range 1.6–88.5 months). Median progression-free survival (PFS) was 4 months (95% CI 2.0–7.9 months), while 6-month PFS was 41.7% (95% CI 22.2–60.1 months). Median overall survival following re-irradiation was 10.7 months (95% CI 7.4–16.1 months). There were no cases of re-operation due to early or late toxicity. Our preliminary results suggest that helical TomoTherapy with the proposed SIB technique is a safe and feasible treatment option for patients with rGBM, including those large disease volumes, reducing toxicity.

MRT-boost as the last fraction may be the most efficient irradiation schedule for increased survival times in a rat glioma model

“…Marchionni et al (2020) improved overall survival by 11 months by delivering a 20 Gy boost (four daily  5 Gy) to glioblastoma patients ( p = 0.004). Five daily fractions of 5 Gy of the 67% isodose (maximum dose in the planning target volume of 37.5 Gy) yielded a significantly longer progression free survival for recurrent glioblastomas (from four months without boost to nine months with boost) (Arpa et al, 2020). MRT would be relevant and efficient for patients for whom a boost or a limited part of a hypo-fractionated treatment is required to increase tumor control or slow recurrence (Kazda et al, 2018).…”