Evaluation of Exposure Doses of Elective Nodal Irradiation in Chemoradiotherapy for Advanced Esophageal Cancer

Simple Summary Surgery has shown that early-stage esophageal cancer is accompanied by extensive lymph node metastasis. Therefore, elective nodal irradiation is indispensable for chemoradiotherapy instead of surgery for the radical cure of esophageal cancer. In contrast, attention must be paid to adverse effects when applying radiation to a wide area. Adverse events are generally more intense with high-dose irradiation. Therefore, determining the appropriate dose for prophylactic irradiation to the elective nodal area is important. However, the appropriate dose has not been fixed. In this study, the therapeutic effects and adverse events of a group of 36 Gy elective nodal irradiation doses were similar to those of 40 Gy or higher. This study's results indicate that preventing lymph node metastasis at lower doses is possible, thus suppressing adverse events. We evaluated elective nodal irradiation (ENI) doses during radical chemoradiotherapy (CRT) for esophageal cancer (EC). A total of 79 patients (65 men and 14 women) aged 52-80 years with T1-3, N0-3, and M0 (including M1ly) who underwent CRT for EC during November 2012-September 2019 were eligible for this retrospective analysis. Patients were divided into two groups: the high-dose group (HG), including 38 patients who received >= 40 Gy as ENI; and the low-dose group (LG), including 41 patients who received <40 Gy. The median doses were 40.0 and 36.0 Gy in HG and LG, respectively. During the follow-up (median: 36.7 months), no lymph node recurrence was observed in the ENI field in all patients. Lymph node recurrence near the ENI field was observed in six patients. No significant differences were observed between the two groups in median overall survival, progression-free survival, and local control. Grade 3-4 acute and late adverse events were observed in five patients of HG and six patients of LG, respectively. No ulceration or stricture was observed in the ENI field on endoscopy examined with 58 Gy irradiation. In conclusion, an ENI dose of 36 Gy could be considered to control the elective nodes of EC.