Comparison of involved field radiotherapy and elective nodal irradiation in combination with concurrent chemotherapy for T1bN0M0 esophageal cancer

Background The optimal radiation field of chemoradiation therapy (CRT) for stage I esophageal squamous cell carcinoma (ESCC) is unknown. This retrospective study compared efficacy and safety of two CRT modalities, involved field irradiation (IFI) and elective nodal irradiation (ENI), when treating patients with clinical stage I (T1bN0M0) ESCC. Methods Patients had received 60 Gy CRT concurrently with 5-FU and cisplatin between January 2000 and December 2012. The clinical target volume of IFI was limited to the primary tumor plus a 2-cm craniocaudal margin; that of ENI covered the primary tumor plus the field of regional lymph nodes. Results One hundred and ninety-five patients were selected (IFI group, 78; ENI group, 117). The 5-year overall, cause-specific and progression-free survival rates were 90.5%, 91.6% and 77.6% in the IFI group, and 72.5%, 88.3%, 57.9% in the ENI group, respectively. Of recurrent patients (n = 16 in the IF and n = 33 in the ENI groups) after achieving complete remission, 12 (75%) in the IFI group received definitive salvage therapy, 11 (33%) patients did in the ENI group. More patients died of diseases other than esophageal cancer in the ENI group (n = 29, 25%) than in the IFI group (n = 3, 3.8%). Multivariate analysis identified ENI (HR 3.63 [1.78-7.38], p < 0.001), age >= 70 (HR 2.65 [1.53-4.58], p < 0.001) and PS = 1 (HR 2.36 [1.33-4.18], p = 0.003) as poor prognostic factors for OS. Conclusions IF irradiation would be better than ENI for the patients with stage I ESCC who received definitive chemoradiotherapy.