Involved-Field Irradiation in Definitive Chemoradiotherapy for T4 Squamous Cell Carcinoma of the Esophagus

Objectives: Definitive concurrent chemoradiotherapy (CCRT) is currently a therapeutic option for locally advanced esophageal cancer. However, clinical practice differs with respect to the target volume for irradiation. The purpose of the present study was to analyze failure patterns and survival, and to determine the feasibility of using involved-field irradiation (IFI) with concurrent chemotherapy for T4 squamous cell carcinoma (SCC) of the esophagus. Methods: Between January 2003 and January 2013, 56 patients with clinical T4M0 SCC of the esophagus received CCRT using IFI. The radiation field included the primary tumour and clinically involved lymph nodes. Target volumes and sites of failure were analyzed, as were treatment-related toxicity and survival time. Results: In this 56-patient cohort, 13 patients (23.2%) achieved a complete response, and 21 (37.5%) achieved a partial response, for a total response rate of 60.7%. The major toxicities experienced were leucocytopenia and esophagitis, with 14 patients (25.0%) experiencing grade 3 toxicities. At a median follow-up of 34 months, 48 patients (85.7%) had experienced failure: 39 (69.6%) in-field, 7 (12.5%) elective nodal, and 19 (33.9%) distant. Only 1 patient (1.8%) experienced isolated elective nodal failure. The 1-, 2-, and 3-year survival rates were 39.3%, 21.4%, and 12.5% respectively. Conclusions: For patients with T4M0 SCC of the esophagus, definitive CCRT using IFI resulted in an acceptable rate of isolated elective nodal failure and an overall survival comparable to that achieved with elective nodal irradiation. A limited radiation therapy target volume, including only clinically involved lesions, would therefore be a feasible choice for this patient subgroup.