Liver Stereotactic Body Radiation Therapy (SBRT) to Downstage Patients with Hepatocellular Carcinoma prior to Liver Transplant

Abstract

Orthotopic liver transplantation (OLT) marks the most successful treatment for hepatocellular carcinoma (HCC) patients meeting Milan criteria. The process of reducing the disease burden of HCC patients not currently meeting criteria for OLT with local therapy is referred to as "downstaging" and has proven to be a feasible approach. RTOG 1112 recently demonstrated the efficacy and acceptable toxicity of liver SBRT for treating HCC. However, limited data currently exists describing the efficacy of SBRT for downstaging HCC patients and facilitating OLT. A single institution IRB approved prospective liver SBRT registry was surveyed for all patients outside of Milan criteria (1 lesion >5 cm; 2-3 lesions >3 cm) without vascular invasion or extrahepatic disease. Patients felt least likely to become OLT candidates with downstaging (age >80, >4 lesions, lesion >12 cm) were excluded. The primary endpoints were downstaging and OLT. Secondary endpoints were time to transplant, local control (LC), recurrence free survival (RFS) and overall survival (OS). A total of 38 HCC patients with a median age of 65 years (range 28 - 80) met inclusion criteria. Median follow up was 14 months (IQR 3 - 35). At baseline, median KPS was 80 (range 60 - 100) with 16 Child-Pugh (CP) A (42%), 13 CP B (34%), and 9 CP C patients (24%). All patients were outside of Milan criteria and 25 patients (66%) were outside of UCSF criteria at time of SBRT. No patients had extrahepatic disease or vascular invasion. Median number of lesions, largest tumor size, and total sum of lesions were 2 (range 1 - 4), 5.0 cm (IQR, 4.0 - 6.5), and 6.6 cm (IQR 5.9 - 9.2), respectively. Prior to SBRT, 22 patients (58%) had received non-SBRT local therapy. At time of SBRT a variety of dose fractionation schedules were selected with a median BED10 of 78 (IQR 62 - 100). Concurrent sorafenib was used in 2 patients (8%). Following completion of SBRT, 21 patients (55%) were successfully downstaged at a median 3.0 months (IQR 1.9 - 6.1) after treatment, most frequently secondary to decrease in size of the largest lesion (86%). Twelve patients (32%) proceeded to undergo OLT at a median 7 months (IQR 3 - 14) after SBRT and 105 days (IQR 18 - 344) following successful downstaging. Of the 25 patients initially exceeding UCSF criteria, 7 (28%) underwent OLT. Among those receiving OLT, 5 patients (42%) remain alive without evidence of disease, 3 patients (25%) have recurred, 3 patients (33%) died within 2 years from transplant complications, and 1 patient (8%) died from an unrelated cause. LC at 2 years was 83%. Median RFS and OS for the overall cohort were 7 months (95% CI 0 - 21) and 24 months (95% CI 11 - 36), respectively. Among the transplant recipients, the median OS was 37 months (95% CI 30 - 44) compared to 15 months (95% CI 6 - 23) among those not receiving transplant. With careful patient selection, liver SBRT serves as a feasible downstaging method to facilitate OLT in HCC patients.