The efficacy and safety of simultaneous integrated dose reduction in clinical target volume with intensity-modulated radiotherapy for patients with locally advanced esophageal squamous cell carcinoma

BACKGROUND: Compelling research to explore the effectiveness of simultaneous integrated dose reduction in clinical target volume (CTV) with intensity-modulated radiotherapy (SIR-IMRT) for locally advanced esophageal squamous cell carcinoma (ESCC) are limited. This study aimed to compare the clinical efficacy and treatment-related toxicity between SIR-IMRT and conventional IMRT (C-IMRT) in the treatment of ESCC. METHODS: From March 2010 to September 2016, the clinical data of 257 patients with ESCC who received definitive IMRT in the Tianjin Medical University Cancer Institute and Hospital were collected and retrospectively analyzed. Among these patients, 137 patients received C-IMRT with a prescribed dose of 60 Gy in 30 fractions for planning target volume (PTV), while 120 patients received SIR-IMRT with a prescribed dose of 60 Gy in 30 fractions for the planning gross tumor volume (PGTV) and a prescribed dose of 54 Gy in 30 fractions for PTV. All of the patients received definitive IMRT with elective nodal irradiation. Locoregional control, survival, treatment toxicity and dose to organs at risk (OAR) were compared between the groups. RESULTS: Patients who received SIR-IMRT showed a similar locoregional failure rate compared to the C-IMRT group (27.5% versus 29.9%, P=0.668). The 1-, 2- and 3-year overall survival (OS) rates were 71.5%, 44.3%, 44.3% vs. 77.9%, 52.1%, 32.9% in the C-IMRT and SIR-IMRT groups, respectively (P=0.825). No significant differences were observed in PFS and LRRFS between the two groups (P=0.880 and P=0.216, respectively). The dose of lung V30 and the maximum dose of spinal cord in the C-IMRT group were significantly higher than those in the SIR-IMRT group (P=0.013, P=0.047). The incidence of acute radiation esophagitis was significantly lower in the SIR-IMRT group (P=0.046), although no statistical difference was observed in the incidence of acute severe adverse events between the two groups. CONCLUSIONS: SIR-IMRT offers an effective and safe option for patients with unresectable ESCC who receive definitive RT. Further prospective and larger sample size studies are warranted to confirm our results.