Long term results of different radiotherapy techniques and fractions for esophageal squamous cell carcinoma

BACKGROUND: Radiotherapy plays an important role in multidisciplinary treatment of esophageal squamous cell carcinoma (ESCC). However, the long term prognosis, relapse and metastasis of patients who received radiotherapy with different radiotherapy technique and fractions were unclear. The objective of the present study was to investigate the correlation of them. METHODS: Six prospective studies were conducted in succession including 475 locally advanced ESCC patients received two-dimensional (2D) and three-dimensional (3D) radiotherapy with late course accelerated hyperfractionated fraction (LCAF) and continuous accelerated hyperfractionated fraction (CAHF). Overall survival was analyzed using the Kaplan-Meier method. Research regarding the incidence of Grade 3 or higher acute radiation-related toxicity was conducted. Details of relapse and metastasis were also investigated. RESULTS: The median follow-up time was 57.5 months. The overall incidence of failure was 49%. No significant survival difference was observed in both LACF vs. CAHF and 2DRT vs. 3DRT groups (P=0.55 and 0.64, respectively). Fewer incidences of acute toxicities were observed in ESCC patients treated with 3DRT compared with those treated with 2DRT (P<0.01). Fewer acute radiation esophagitis was observed in LCAF comparison of CAHF (P<0.01), however no significant difference of acute radiation pneumonitis was observed. A total of 65 patients were considered to have metastatic disease affecting distant organs: lung (n=39, 8.2%), liver (n=35, 7.4%) and bone (n=21, 4.4%). CONCLUSIONS: About half of patients suffered local/regional failure following radiotherapy. 3DRT reduced acute radiotherapy toxicities compared with 2DRT. LCAF was more tolerant than CAHF.