Radiotherapy (RT) is considered to be an effective alternative to surgery for the treatment of patients with EC.9 Although the landmark RTOG 85 − 01 trial established the CCRT as the standard therapy for EC, its side effects were serious.10 Previous studies have found that the efficacy of conventional fractionated radiotherapy is unsatisfactory, the repopulation of surviving tumor cells during treatment with radiation is an important cause of treatment failure, and unconventional fractionated radiotherapy can better inhibit the accelerated proliferation of tumor cells, thus obtaining greater treatment gain ratio.11 Based on this concept, LCAFRT for EC has been widely utilized. In the 2DRT era, Shi XH et al. have reported that compared to CFRT, LCAFRT can increase the 5-year survival rate of EC patients from 15–34%.12 Zhao KL et al. have analyzed 201 ESCC patients treated by LCAFRT. Their results have shown that 1-, 3-, and 5-year overall survival rates were 73%, 34%, and 26%, respectively, while 1-, 3-, and 5-year local control rates were 77%, 58%, and 56%, respectively. Their treatment resulted in similar local control and survival rates when using standard chemotherapy plus RT, such as was delivered in the RTOG 85 − 01 and 94-05.13 Several other studies14–16 have also indicated that the curative effect of LCAFRT was better than that of CFRT. However, the use of continuous accelerated hyperfractionated radiotherapy17 or late-course accelerated hyperfractionation combined with chemotherapy15,18 does not significantly increase the efficacy due to toxicity. With the continuous update of radiotherapy equipment in recent years, the conformal radiotherapy technique has been adopted instead of conventional radiotherapy method. Few studies have shown the efficacy of late-course accelerated hyperfractionated conformal radiotherapy. Wang JH et al. have used three-dimensional conformal radiotherapy to treat 98 patients with esophageal cancer, including 48 cases with LCAFRT. The result showed that the 1-, 2-, and 3-year local control and survival rates for LACFRT were 81.3%, 62.5%, and 50% and 79.2%, 56.3%, and 43.8%, respectively. However, the radiation side-effects were greater in LACFRT.19 Zhang DF et al. have shown that the therapeutic effect of whole-course 3DCRT combined with LCAFRT for EC is superior to conventional radiotherapy, with the 1, 2, and 3-year tumor local control and overall survival rates of 87.8%, 75.5%, and 63.3% and 85.7%, 71.4%, and 46.7%, respectively.20 In the present study, the five-year local control and survival rates were 68.18% and 41.82%, respectively. Compared to the previous studies, this method offers obvious advantages, which might be due to the fact that conformal radiotherapy elevated the local irradiation dose and homogeneity. The efficacy of 3D-CRT technique or intensity-modulated radiation therapy (IMRT) is similar, but the incidence of radiotherapy-related adverse reactions due to IMRT is lower. The results of multivariate analysis showed that the prognosis of patients with lesions located in the lower thoracic segment and with TNM stage III and IV were poor. In the analysis of the causes of death, local uncontrolled regional recurrence and distant metastasis were still the main causes of death. IMRT may thus be more advantageous for local control.
Overall, the present results revealed that the survival rate for patients with esophageal cancer treated by whole-course conformal radiotherapy and LCAFRT was significantly higher than that for patients treated with conventional technology. IMRT had more advantages in local control and fewer radiotherapy-related adverse reactions. These results need to be further confirmed using prospective studies.