Dose escalation in radiotherapy for incomplete transarterial chemoembolization of hepatocellular carcinoma

To investigate the efficacy of radiation dose escalation in patients with hepatocellular carcinoma (HCC) after incomplete transarterial chemoembolization (TACE).

This study evaluated retrospective data of 323 HCC patients who received radiotherapy after incomplete TACE from 2001-2016. Radiation dose in biologically effective dose (BED) (α/β = 10) was categorized as <72 Gy (261 patients) and ≥72 Gy (62 patients). Simultaneous integrated boost-intensity modulated radiation therapy (SIB-IMRT) was used significantly more frequently in the high-dose group (64.5% vs. 12.9%; P < 0.001). Local failure-free rate (LFFR), progression-free rate (PFR), and toxicities were compared between the two groups. Additionally, propensity score matching was performed.

Median follow-up time for patients who were alive at the time of analysis was 47 months (range 18-189 months). Median overall survival after radiotherapy was 14 months. In multivariate analysis, BED ≥72 Gy was an independent predictor of favorable LFFR (hazard ratio [HR] 0.32; 95% confidence interval [CI] 0.14-0.72; P = 0.006) and PFR (HR 0.67; 95% CI 0.45-0.98; P = 0.04). In the propensity score-matched cohort (62 pairs), 1‑year LFFR (94% vs. 81%; P = 0.002), and 1‑year PFR (49% vs. 42%; P = 0.01) were significantly higher in the high-dose group. Treatment-related toxicities were comparable between the high-dose and low-dose groups (classic radiation-induced liver disease: 5.3% [3/57] vs. 13.8% [29/210], P = 0.08; grade 2-4 gastrointestinal bleeding: 3.2% [2/62] vs. 7.3% [19/261], P = 0.39).

Radiation dose with BED ≥72 Gy improved LFFR and PFR without increasing toxicity. In radiotherapy for incomplete TACE of HCC, dose escalation using SIB-IMRT should be actively considered to improve oncologic outcome.