355 - Survival Prediction with Albumin-Bilirubin (ALBI) Changes in Hepatocellular Carcinoma Patients Treated with External Beam Radiotherapy (EBRT)

K. Thonglert¹, S. Apisarnthanarax², M. Nyflot², S. R. Bowen², Y. He², J. Tsai³, I. Chamseddine⁴, J. Pursley⁴, H. J. Roberts⁴, J. Y. Wo⁴, B. Y. Yeap⁵, T. S. Hong⁴, A. Prayongrat¹, P. Alisanant¹, N. Amornwichet¹, C. Khorprasert¹, and C. Grassberger²; ¹Division of Radiation Oncology, Department of Radiation, Faculty of Medicine, Chulalongkorn University, King Chulalongkorn Memorial Hospital, Bangkok, Thailand, ²Department of Radiation Oncology, University of Washington/ Fred Hutchinson Cancer Center, Seattle, WA, ³Department of Radiation Oncology, University of Washington, Seattle, WA, ⁴Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, ⁵Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA

Purpose/Objective(s): The Albumin-Bilirubin (ALBI) score offers a simpler, less subjective alternative for evaluating liver function in patients with hepatocellular carcinoma (HCC). However, data on its application in assessing hepatotoxicity post-EBRT are limited. This study aims to establish ALBI score change thresholds as indicators for hepatotoxicity that correlate with a worse survival outcome. Materials/

Methods: The development cohort consisted of 329 HCC patients who received liver-targeted EBRT across two centers from 2008 to 2023. ALBI score change was defined as the difference between baseline and the score within four months post-EBRT. Recursive partitioning analysis was used to identify thresholds that correlate with overall survival (OS), which were evaluated using Cox-regression. Findings were compared to changes in Child-Pugh (CP) score by 2 points (CP+2) and externally validated with a dataset from an independent center (N = 114).
Results: Continuous changes in the ALBI score were significantly associated with OS (Hazard Ratio (HR) 2.3, 95% CI 1.7-2.8). ALBI changes of >0.25 (grade 1) and >0.5 (grade 2) were identified as optimal thresholds. For the development cohort, CP+2 showed superior discriminative performance; however, when stratifying by baseline liver status (Table 1), grade 1 ALBI change demonstrated improved predictive capability in CP-B/C patients (HR 4.4, 95%CI 2.4-7.8). Overall, these findings were confirmed in the external validation cohort, with grade 2 ALBI score changes being most prognostic for survival (HR 5.0, 95% CI 2.9-8.5). Multivariable Cox models including CP+2 or ALBI changes and baseline liver status demonstrated higher concordance for ALBI score changes across all datasets. Furthermore, ALBI score changes correlate better with mean liver dose (point-biserial correlation r= 0.29/0.22 for grade 1/2) compared to CP+2 (r=0.14)
Conclusion: ALBI score changes of >0.25 (grade 1) and >0.5 (grade 2) are an alternative to CP+2 to evaluate radiation hepatotoxicity and have the potential to assess significant changes more accurately depending on the patient’s baseline liver function. Their increased correlation to dose to the normal liver makes them more suitable for dose-response models aimed at individualizing dose to minimize risk of liver complications after EBRT.

Abstract 355 – Table 1: Hazard Ratios (HRs) for Overall Survival (OS) Based on ALBI and CP Score Changes

	Development Cohort						Validation Cohort
	All (n = 329)		CP-A (n=233)		CP-B/C (n=96)		All (n = 114)
	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
?ALBI > 0.25 (grade 1)	2.5 (1.9-3.4)	<0.001	2.2 (1.6-3.1)	<0.001	4.4 (2.4-7.8)	<0.001	2.4 (1.5-3.9)	<0.001
?ALBI > 0.5 (grade 2)	2.3 (1.7-3.1)	<0.001	2.5 (1.7-3.6)	<0.001	1.9 (1.1-3.4)	0.017	5 (2.9-8.5)	<0.001
?CP = 2	4.5 (3.2-6.2)	<0.001	4.6 (3.1-6.9)	<0.001	3.7 (2.1-6.5)	<0.001	3.3 (1.9-5.7)	<0.001