Treatment

The dCRT regimen followed the standard-dose cisplatin plus fluorouracil regimen of JCOG0303 [4]. Chemotherapy consisted of intravenous infusion of 70 mg/m² cisplatin with adequate hydration on days 1 and 29, and continuous infusion of 700 mg/m² fluorouracil on days 1–4 and 29–32. For an antiemetic, the infusion of dexamethasone and palonosetron hydrochloride along with oral or infused aprepitant was used, after they had been approved for antiemesis. Additional cisplatin plus fluorouracil doublet therapy was continued as necessary after dCRT. RT was planned to deliver a total of 60 Gy/30 Fr using a linear accelerator with a 6-, 10-, or 18-MV photon beam. Three-dimensional dose calculations were performed using Pinnacle3 software (ADAC, Milpitas, CA) with correction for tissue-density inhomogeneity. The treatment planning was based on 3.8- to 5-mm-thick CT scans obtained in the treatment position. The gross tumor volume was based on clinical examinations including CT scan and endoscopy. The clinical target volume (CTV) for the primary tumor was created to add a 2-cm margin craniocaudally to account for subclinical tumor extension. A CTV margin for metastatic lymph nodes was not added. Elective nodal irradiation was not performed. The planning target volume (PTV) was created to add 0.5–1 cm for lateral margins and 1–1.5 cm for craniocaudal margins. The radiation fields were designed to cover the PTV with an adequate margin. A dose of 60 Gy to the center of the PTV was prescribed. The dose to the spinal cord was kept at ≤45 Gy. The mean doses of the heart and the volume of the lung receiving 20 Gy (V20) were kept at ≤40 Gy and ≤ 35%, respectively.