ALBI-RT: A novel radiation therapy specific hepatotoxicity prediction model for hepatocellular carcinoma patients.

Abstract

444 Background: The albumin-bilirubin (ALBI) grade system was optimized to predict survival in hepatocellular carcinoma (HCC) patients; however, its applicability to patients treated with radiation therapy (RT) is unclear. We propose a novel analysis of the ALBI equation, designated ALBI-RT, to assess hepatotoxicity risk after RT. Methods: We retrospectively reviewed 48 consecutive HCC patients treated with RT (2013-2016). Raw ALBI values and Child-Pugh (CP) scores were calculated. Any patient deaths were examined for radiation induced liver disease (RILD). Raw ALBI was assessed as a continuous variable to perform ROC analyses to identify cutoffs for overall survival (OS) and RILD-specific survival (RILD-SS). Univariate predictors of OS and RILD-SS were evaluated using Cox regression to determine hazard ratios (HR). Results: Patient cohort was comprised of 60% CP-A and 39% CP-B/C. Median follow-up and OS was 13 and 10 months, respectively. There were 18 deaths with 6 ascribed to RILD. We identified a raw ALBI cutoff at -1.70 (AUC = 0.94, p = 0.008) that was predictive of RILD-SS with a sensitivity of 100% and specificity of 71%. Dichotimization of RILD-SS cutoff generated two ALBI-RT risk categories: low-risk A < -1.70 (n = 29) and high-risk B ≥ -1.70 (n = 18). ALBI-RT subdivided CP-A patients, identifying 14% at increased risk of RILD; conversely, ALBI-RT grade A identified 21% of CP-B/C patients at a decreased risk of RILD. For OS, raw ALBI as a continuous variable (HR 3.0, p = 0.02), and to a lesser degree ALBI-RT Grade B (HR 2.4, p = 0.06), performed similarly to traditional ALBI grade (HR 3.0, p = 0.01), and CP score (HR 1.4, p = 0.03). In contrast for RILD-SS, raw ALBI as a continuous variable (HR 25.1, p = 0.01) and ALBI-RT Grade B (HR 9.9, p = 0.04) were associated with an elevated relative risk of RILD than traditional ALBI grade (HR 5.8, p = 0.02) and CP score (HR 2.3, p = 0.003). Conclusions: ALBI-RT is a promising metric for pre-treatment assessment of HCC patients for predicting RILD-related death after RT with an elevated relative-risk compared to both CP and conventional ALBI grades. Future prospective evaluation and validation in independent data sets will strengthen the generalizability and utility of ALBI-RT.