Proton Beam Radiation Therapy (PBRT) for Downstaging and/or Bridge Therapy for Hepatocellular Carcinoma (HCC) Prior to Liver Transplant (LT)

Abstract

Introduction: PBRT has been shown to be an effective treatment against several types of malignancies. In this study, we reviewed the results of our long-term experience with the use of PBRT for the treatment of HCC prior to LT. Methods: LT candidates with HCC diagnosed by standard CT or MRI imaging criteria underwent PBRT at the recommendation of a multidisciplinary treatment team. Indications for treatment included downstaging of patients with HCC to within Milan criteria and/or bridge therapy prior to LT. PBRT was administered as 15 fractions over a 3-week period (63 Gy delivered in 4.2 Gy daily fractions). Imaging with either CT or MRI was obtained 1-month post-treatment, then every 3 months until LT to monitor effectiveness of treatment. Tumor recurrence while awaiting LT was treated with PBRT, chemoembolization, or ablative therapy. Patients with HCC meeting the UCSF criteria were listed after successful downstaging to Milan criteria according to Region 5 policy. MELD HCC upgrades were done according to UNOS policy. Surveillance imaging post-transplantation was conducted for up to 5 years. Results: 82 of 437 (19%) patients transplanted at our center had HCC; 28 of these patients were treated with PBRT. Time from diagnosis of HCC to LT was 14.5 +/- 13 months, consistent with the long wait times in our donor service area. Due to an inadequate treatment response, 1 patient underwent transarterial chemoembolization (TACE) after PBRT. Mean MELD at the time of transplant was 33 +/- 4. Pathologic exam showed that a significant number of patients in the PBRT cohort had no identifiable tumor in the explant. Recurrence of HCC occurred in only 1 patient who died 13 months post LT. One- and 5-year patient survival was 89% and 66%. Conclusions: PBRT is a promising and effective treatment modality for the management of HCC prior to LT.