Details of out-field regional recurrence after involved-field irradiation with concurrent chemotherapy for locally advanced esophageal squamous cell carcinoma

BACKGROUND: The purpose of this study was to describe the patterns of out-field regional recurrence after involved-field irradiation (IFI) in definitive concurrent chemoradiotherapy (CCRT) for locally advanced esophageal squamous cell carcinoma (LA-ESCC) and identify the possible risk factors. PATIENTS AND METHODS: Eighty patients with LA-ESCC who received CCRT with IFI between January 2003 and January 2009 at the Shandong Cancer Hospital were recruited and analyzed. Imaging scans demonstrating first sites of failure were compared with original computed tomography-based radiation treatment plans, and failure patterns were defined as in-field, outfield regional (failures in initially uninvolved regional nodes), and distant failures. RESULTS: After a median follow-up time of 52.6 months, 24 patients had evidence of out-field regional failure, 43 patients had evidence of in-field failure, and 33 patients had the evidence of distant failure. Multivariate analysis revealed that out-field regional failure was associated with clinical tumor status (T4 vs T1–3, odds ratio [OR] =6.547, P=0.002), tumor length (>8 cm vs ≤8 cm, OR =4.130, P=0.036), response to CCRT (complete response vs no complete response, OR =2.646, P=0.035), and in-field failure (no in-field failure vs in-field failure, OR =1.32, P=0.016). Survival analyses indicated that, compared to in-field failure or distant failure alone group, out-field regional failure alone group tended to have longer overall (P=0.006) and progression-free survival (P=0.164). CONCLUSION: Our data suggested that the predominant failure pattern after IFI was not out-field regional failure, which also did not influence survival significantly, and that out-field regional failure did not shorten the time to disease recurrence, which also did not influence survival significantly. In addition, out-field regional failure was likely to appear later than in-field and distant failures. The relatively advanced local disease followed by poor local control and distant metastases contributed more to the poor outcome of LA-ESCC. Further prospective studies are needed to verify the findings of this study.