Top Line: Have you ever been tempted to harness the impressive dosimetry of ablative radiation for small primary non-small cell lung cancer (NSCLC) tumors even in the setting of nodal disease?
The Study: We know, we know, there’s no evidence for this approach…or is there? After all, it would only add a few days upfront before proceeding with standard conventionally-fractionated chemoradiation to the nodal disease. That’s exactly what this single-arm phase 2 trial of 60 patients investigated. Important inclusion criteria included primary tumor size <7 cm and at least a 2 cm separation of primary tumor from involved nodes. Both radiation courses were planned on the same initial 4D CT simulation. Abdominal compression was used for tumors with a high degree of movement, but the authors recognize breath hold could be used, too. There was no clinical target volume (CTV) expansion on the primary gross tumor volume drawn on all phases of the 4D scan (iGTVp) which then was expanded radially by 0.5 cm to create the planning target volume (PTVp). This was preferably prescribed 54 Gy in 3 fractions, unless it was central with overlap with nodal volumes in which case it was prescribed a more conservative 50 Gy in 4-5 fractions. The nodal volume was prioritized as an avoidance structure unless failing to meet any dose constraints to organs at risk (table 2). A sequential plan of 60 Gy in 30 fractions via VMAT to standard nodal volumes was then created using any dose fall-off from initial SBRT as a base dose with plan sum evaluation, and this was delivered with standard concurrent platinum-based doublet chemo. At a median follow-up of two years, 5% (n=3) of enrollees experienced grade 3 pneumonitis and one patient grade 3 esophagitis, which compares favorably to historic controls with standard chemoradiation to all gross disease.
TBL: The follow-on large-scale phase 3 LU-008 trial will randomize patients with locally-advanced NSCLC across multiple institutions to this approach versus the longtime standard of chemoradiation to all gross diseases prior to maintenance immunotherapy. | Heinzerling, Pract Radiat Oncol 2023
The Study: We know, we know, there’s no evidence for this approach…or is there? After all, it would only add a few days upfront before proceeding with standard conventionally-fractionated chemoradiation to the nodal disease. That’s exactly what this single-arm phase 2 trial of 60 patients investigated. Important inclusion criteria included primary tumor size <7 cm and at least a 2 cm separation of primary tumor from involved nodes. Both radiation courses were planned on the same initial 4D CT simulation. Abdominal compression was used for tumors with a high degree of movement, but the authors recognize breath hold could be used, too. There was no clinical target volume (CTV) expansion on the primary gross tumor volume drawn on all phases of the 4D scan (iGTVp) which then was expanded radially by 0.5 cm to create the planning target volume (PTVp). This was preferably prescribed 54 Gy in 3 fractions, unless it was central with overlap with nodal volumes in which case it was prescribed a more conservative 50 Gy in 4-5 fractions. The nodal volume was prioritized as an avoidance structure unless failing to meet any dose constraints to organs at risk (table 2). A sequential plan of 60 Gy in 30 fractions via VMAT to standard nodal volumes was then created using any dose fall-off from initial SBRT as a base dose with plan sum evaluation, and this was delivered with standard concurrent platinum-based doublet chemo. At a median follow-up of two years, 5% (n=3) of enrollees experienced grade 3 pneumonitis and one patient grade 3 esophagitis, which compares favorably to historic controls with standard chemoradiation to all gross disease.
TBL: The follow-on large-scale phase 3 LU-008 trial will randomize patients with locally-advanced NSCLC across multiple institutions to this approach versus the longtime standard of chemoradiation to all gross diseases prior to maintenance immunotherapy. | Heinzerling, Pract Radiat Oncol 2023