Prospective trial of functional liver image-guided hepatic therapy (FLIGHT) with hepatobiliary iminodiacetic acid (HIDA) scans and update of institutional experience.

Abstract

373 Background: Functional liver image-guided hepatic therapy (FLIGHT) is a novel stereotactic body radiation therapy (SBRT) planning technique. A functional map, generated from hepatobiliary iminodiacetic acid (HIDA) scans, is used to maximize the functional residual capacity of liver receiving < 15 Gy (FRC15HIDA). We present initial results of a prospective trial evaluating FLIGHT vs standard planning and update our institutional experience. Methods: Eligible patients were ≥ 18 yo with 1o or 2o liver malignancy and Child-Pugh ≤ B7. Liver function was assessed with HIDA and blood chemistry at baseline, mid-treatment, and 3, 6, and 12 months post SBRT. Both standard and FLIGHT (optimized to avoid high functioning liver) plans were generated for each patient. Treating MDs were blinded to planning technique before selecting the treatment plan. The primary endpoint was to show > 5% increase in FRC15HIDA in 3/15 pts. Secondary endpoints included the rate FLIGHT plans were selected and changes in HIDA and other liver function tests. Prior institutional experience included 27 pts with FLIGHT planned retrospectively. Paired t-test was used to compare dosimetric endpoints for FLIGHT vs. standard plans, including: FRC15HIDA, mean liver dose, effective uniform dose (EUD), and functional EUD (FEUD). Results: Fifteen pts were enrolled. The primary endpoint was met, as 4/15 pts had > 5% improvement in FRC15HIDA (mean 5.2%, range -2.3-19.8%). Notably, the FLIGHT plan was selected in 11/15. The mean improvements in FRC15HIDA (5.2 vs 5.0%), mean liver dose (11.9 vs. 13.0%), EUD (5.1 vs 5.2%), and FEUD (6.9 vs 7.1%) were similar between prospective and retrospective cohorts (p > 0.5). In the entire cohort (n = 42), FLIGHT improved FRC15HIDA, mean liver dose, EUD, and FEUD ( p ≤ 0.001). There were > 5% improvements in FRC15HIDA in 15, mean liver dose in 31, EUD in 19, and FEUD in 27. Conclusions: FLIGHT with HIDA led to improvements in all analyzed dosimetric parameters. The extent of benefit was similar in both cohorts, and there was individual variation in the extent of benefit. Longer follow-up is required to determine the effect of FLIGHT on post-SBRT liver function. Clinical trial information: NCT03338062.