Analysis of Radiation Segmentectomy Treatment Planning in DOORwaY90: Selective Internal Radiation Therapy Using SIR-Spheres Y-90 Resin Microspheres as First-line Treatment for Unresectable Hepatocellular Carcinoma Patients

Purpose: DOORwaY90, a prospective, multicenter, open-label, single-arm study, evaluated the safety and efficacy of ⁹⁰Y-resin microspheres as first-line treatment for local tumor control in unresectable HCC. Patients were treated using partition dosimetry with T:N =1 for radiation segmentectomy patients (2 or few segments).

Materials and Methods: Trial inclusion criteria: HCC patients ineligible for resection or ablation, BCLC A-C with maximal single lesion size ≤8cm, and sum of diameters ≤12cm. Sixty one patients from 18 centers were treated using radiation segmentectomy with planned target mean dose to the perfused volume from 150-400 Gy. Cone beam CT or Angio CT imaging and T99m MAA SPECT/CT were used for treatment planning. All patients were treated with 3 Day pre-calibration microspheres. All treatment plans were reviewed with the site PI and national PIs using MIM software for contours and volume calculation. Post treatment SPECT/CT and PET/CT were used for treatment dose verification.

Results: The median and mean planned doses for radiation segmentectomy 300.0 (150.0-400.0) and 319.8 +/- 79.5. The median planned perfused volume of treatment was 249 ml (31 - 456 ml). The median and mean actual tumor doses 566.4 (121.4-1915.3) and 633.5 +/- 373.7. The ORR for the study was 98.5% with a CR of 92.5%.

Conclusion: Interim analysis of DOORwaY90 data demonstrated a positive study with favorable safety and efficacy and very high CR rates for radiation segmentectomy.