title: Charged particle therapy versus photon therapy for patients with hepatocellular carcinoma: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To perform a systematic review and meta-analysis to compare the clinical outcomes and toxicity of hepatocellular carcinoma (HCC) patients treated with charged particle therapy (CPT) with those of individuals receiving photon therapy.
  
  
  METHODS
  We identified relevant clinical studies through searching databases. Primary outcomes of interest were overall survival (OS) at 1, 3, 5 years, progression-free survival (PFS), and locoregional control (LC) at longest follow-up.
  
  
  RESULTS
  73 cohorts from 70 non-comparative observational studies were included. Pooled OS was significantly higher at 1, 3, 5 years for CPT than for conventional radiotherapy (CRT) [relative risk (RR) 1·68, 95% CI 1·22-2·31; p<0·001; RR 3.46, 95% CI: 1.72-3.51, p<0.001; RR 25.9, 95% CI: 1.64-408.5, p=0.02; respectively]. PFS and LC at longest follow-up was also significantly higher for CPT than for CRT (p=0·013 and p<0.001, respectively), while comparable efficacy was found between CPT and SBRT in terms of OS, PFS and LC at longest follow-up. Additionally, high-grade acute and late toxicity associated with CPT was lower than that of CRT and SBRT.
  
  
  CONCLUSIONS
  Survival rates for CPT are higher than those for CRT, but similar to SBRT in patients with HCC. Toxicity tends to be lower for CPT compared to photon radiotherapy.
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, China.
authors.forename: Wei-Xiang
authors.initials: WX
authors.lastname: Qi
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, China; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, China. Electronic address: fushen2014@sina.com.
authors.forename: Shen
authors.initials: S
authors.lastname: Fu
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, China; Department of Radiation Oncology, Fudan University Shanghai Cancer Center, China.
authors.forename: Xiao-Mao
authors.initials: XM
authors.lastname: Guo
mesh_terms: D000512:Alpha Particles / Q000627:therapeutic use; D006528:Carcinoma, Hepatocellular / Q000532:radiotherapy*; D015331:Cohort Studies; D018572:Disease-Free Survival; D006801:Humans; D008113:Liver Neoplasms / Q000532:radiotherapy*; D064887:Observational Studies as Topic; D017785:Photons / Q000627:therapeutic use*; D015996:Survival Rate
keywords: Carbon-ion; Hepatocellular carcinoma; Meta-analysis; Photon; Proton; Radiotherapy