Liver toxicity following reirradiation and multiple-target SBRT for primary hepatocellular carcinoma.

Abstract

514 Background: Stereotactic body radiation therapy (SBRT) is increasingly used to treat hepatocellular carcinoma (HCC), but its safety in the treatment of multiple synchronous or recurrent lesions is underreported. We aim to better characterize SBRT-related hepatic toxicity in this population. Methods: We conducted a retrospective analysis of patients with primary HCC who underwent SBRT for 2 or more synchronous or recurrent liver lesions. We collected patient characteristics and dosimetric data (mean liver dose, cumulative effective volume [Veff], cumulative volume of liver receiving 15Gy [V15Gy], and cumulative planning target volume [PTV]) along with liver-related toxicity (measured by albumin-bilirubin [ALBI] and Child-Pugh [CP] scores). We employed a linear mixed-effects model to assess the effect of multi-target SBRT on changes in ALBI. Results: There were 25 patients and 56 lesions with median follow-up of 29 months. Eleven patients had synchronous lesions and 14 had recurrent lesions treated with separate SBRT courses. Eight local failures occurred at a median of 8 months (range: 4 – 25 months) after SBRT. Among those receiving multiple SBRT courses, there were 7 lesions with overlap of V15Gy (median V15Gy overlap: 35mL, range: 0.5 – 388mL). There was no association between cumulative Veff, V15Gy, or PTV and change in ALBI. Four of 25 patients an increase of Child-Pugh (CP) score by ≥ 2 points, within 3 to 6 months after SBRT. Neither increase in CP nor ALBI were associated with cumulative Veff, V15Gy, and PTV. Comparing the groups that received SBRT in a single course versus multiple courses revealed no statistically significant differences in liver toxicity. Conclusions: LiverSBRT for multiple lesions in a single or in separate courses results in worsening of CP scores or ALBI in a small percentage of patients, suggesting a low risk of RILD. Prospective studies with a larger cohort are needed to better characterize safety in this population.