Proton boost in liver cancerRisk-adapted simultaneous integrated boost-proton beam therapy (SIB-PBT) for advanced hepatocellular carcinoma with tumour vascular thrombosis

PurposeTo evaluate clinical effectiveness and safety of simultaneous integrated boost-proton beam therapy (SIB-PBT) in hepatocellular carcinoma (HCC) patients with tumour vascular thrombosis (TVT).Material and methodsForty-one HCC patients with TVT underwent SIB-PBT using three dose-fractionation schemes: if gross tumour volume <1 cm (n = 27), 1-1.9 cm (n = 7), and ⩾2 cm (n = 7) from gastrointestinal structures, 50 GyE (EQD2, 62.5 GyE10), 60 Gy (EQD2, 80 GyE10), 66 Gy (EQD2, 91.3 GyE10), respectively, in 10 fractions was prescribed to planning target volume 1 (PTV1), and 30 GyE (EQD2, 32.5 GyE10) in 10 fractions was prescribed to PTV2.ResultsOverall, treatment was well tolerated, with no grade toxicity ⩾3. Median overall survival (OS) was 34.4 months and 2-year local progression-free survival (LPFS), relapse free survival (RFS), and OS rates were 88.1%, 25%, and 51.1%, respectively. Patients treated with EQD2 of ⩾80 GyE10 tended to show better TVT response (92.8% vs. 55.5%, p = 0.002) 2-year LPFS (92.9% vs. 82.5%, p = 0.463), RFS (28.8% vs. 19%, p = 0.545), and OS (58.4% vs. 46.8%, p = 0.428) rates than those with EQD2 of <80 GyE10. Multivariate analysis showed that TVT response and Child Pugh classification were independent prognostic factors for OS.ConclusionsSIB-PBT is feasible and promising for HCC patients with TVT.