Long-Term Results of a Phase I Dose-Escalation Trial and Subsequent Institutional Experience of Single-Fraction Stereotactic Ablative Radiation Therapy for Liver Metastases
Menée auprès de 33 patients présentant des métastases hépatiques ayant pour origine une tumeur solide (durée médiane de suivi : 25,9 mois), cette étude évalue la dose maximale tolérée et la toxicité d'un traitement par radiothérapie stéréotaxique
Purpose/Objectives: We report long term outcomes from our phase I dose-escalation study to determine the maximum tolerated dose of single-fraction liver stereotactic ablative radiotherapy (SAbR) pooled with our subsequent single institutional experience with patients treated post-protocol at the highest dose level (40 Gy) established from the Phase I study. Materials/Methods: Patients with liver metastases from solid tumors located outside of the central liver zone were treated with single-fraction SAbR on a Phase I dose escalation trial. At least 700 cc of normal liver had to receive <9.1 Gy. Seven patients with 10 liver metastases received the initial prescription dose of 35 Gy, and dose was then escalated to 40 Gy for 7 more patients with 7 liver metastases. An additional 19 post-protocol patients with 22 liver metastases were treated to 40 Gy in a single fraction. Patients were followed for toxicity and underwent serial imaging to assess local control. Results: Median imaging follow-up for the combined cohort (n=33, 39 lesions) was 25.9 months; 38.9 months for protocol patients and 20.2 months for post-protocol patients. Median lesion size was 2.0 cm (range 0.5-5.0 cm). There were no dose-limiting toxicities observed for protocol patients, and only three Grade 2 toxicities were observed in the entire cohort, with no Grade ≥ 3 toxicities attributable to treatment. Four-year actuarial local control of irradiated lesions in the entire cohort was 96.6%; 100% in the protocol group and 92.9% in the subsequent patients, respectively. Two-year overall survival for all treated patients was 82.0%. Conclusion: For selected patients with liver metastases, single-fraction SABR at doses of 35 and 40 Gy was safe and well-tolerated, and shows excellent local control with long term follow-up; results in subsequent patients treated with single-fraction SAbR doses of 40 Gy confirm our earlier results.
International Journal of Radiation Oncology, Biology, Physics 2020