Author: E Courtney Henry, Srinivas Cheenu Kappadath, Armeen Mahvash 👨🔬
Affiliation: UT MD Anderson Cancer Center 🌍
Purpose:
Characterization of hepatocellular carcinoma (HCC) tumor responses for single-arm single-center prospective 90Y-radioembolization clinical trial (n=40) that used patient-specific voxel-dosimetry-based treatment planning (NCT03896646).
Methods:
Eligibility criteria included adult HCC patients with non-infiltrative tumor diameters ≥3 cm otherwise eligible for 90Y-glass radioembolization. All patients underwent hepatic angiography CT (AngioCT), received 99mTc-MAA injections at all sites of treatment, and underwent SPECT/CT imaging. Fused AngioCT and 99mTc-MAA SPECT/CT was used to plan tumor mean-voxel dose ≥200 Gy and normal liver mean-voxel dose ≤100 Gy. Post-treatment dose verification was performed using 90Y-SPECT/CT and 90Y-PET/CT. Localized mRECIST tumor responses were determined at 6-month follow-up. We characterize tumor response relationships, based on 37 patients (51 tumors) who completed 6-month follow-up, with size and dose-coverage metrics.
Results:
The DCR [=(CR+PR+SD)/(CR+PR+SD+PD)] was 100%, with 95% ORR [=(CR+PR)/(CR+PR+SD+PD)], and 58% CRR [=(CR)/(CR+PR+SD+PD)]. The median (range) tumor effective diameter was 4.5 (2.9-12.3) cm; with 37%<4cm, 63%<6cm, and 14%>8cm. The median (range) tumor voxel-dose delivered was 351 (172-981) Gy; with 98%>200Gy, 74%>300Gy, and 35%>400Gy. The Welch's t-test reported non-significant differences (p=0.15) in tumor mean-dose for CR (427Gy) versus others (363Gy); but significant differences (p=0.0016) in size for CR (4.4cm) versus others (7.0cm). Non-significant differences were also observed when assessing other dose-coverage metrics: D50, D70, D90, D70-50_gradient, D90-50_gradient. Multi-variate logistic regression showed tumor size was prognostic of CR with odd’s ratio 0.58 (95%CI:0.36-0.81) and ROC curve AUC 0.79 (95%CI:0.65-0.94, p=0.0013). The threshold size for CR was estimated as <5.6cm with sensitivity of 88% and specificity of 72%. Dose heterogeneity was not correlated with tumor size.
Conclusion:
The feasibility and efficacy of prospective, patient-specific, MAA-based voxel dosimetry treatment planning for 90Y-radioembilization has been demonstrated. Tumor voxel-dose of >200 Gy were achieved in 98% cases resulting in ORR=95% and CRR=58% with size (<5.6cm) as the only prognostic indicator for CR.