Radiotherapy (RT) dose escalation study with concurrent cisplatin and S-1 in patients with inoperable stage III non-small cell lung cancer (NSCLC)
7542 Background: Standard treatment for inoperable stage III NSCLC is concurrent chemoradiotherapy using 3-D conformal RT to a total dose of 60 Gy, but the outcome is still dismal with median survival time (MST) of 16 months and 5-year survival of 15%. We conducted a phase II trial using cisplatin, S-1 and concurrent RT of 60 Gy (J Clin Oncol 2008;26:a7556). MST (33months) was encouraging, however, local failure rate with this trial remained still high. The purpose of this study was to establish the recommended dose (RD) of RT with concurrent cisplatin and S-1. Methods: The eligibility criteria were: histologically or cytologically proven NSCLC, 20–75 years old, performance status 0–1, without any prior chemotherapy or RT. Patients were treated with cisplatin (60 mg/m2 on day 1) and S-1 (orally at 40 mg/m2/dose b.i.d., on days 1–14) repeated every 4 weeks for 4 cycles and RT was started on day 1. Radiation dose was escalated from 66 Gy in 33 fractions (Arm 1) to 70 Gy in 35 fractions (Arm 2), then 74 Gy in 37 fractions (Arm 3). The dose was to be escalated if DLTs were observed in 2 or less patients. The target volume of RT included primary tumor and metastatic node only and elective nodal irradiation was not performed. Dose constraints to the organs at risk were: the lung, V20 < 30%; the esophagus, mean dose < 34 Gy and V55 < 30%; the spinal cord, max dose < 50 Gy. Results: Six patients in each arm were enrolled. Two patients in Arm 1 experienced DLTs: one patient developed grade 3 febrile neutropenia, grade 3 mucositis in oral cavity and grade 3 diarrhea and one patient developed grade 3 febrile neutropenia. One patient in Arm 3 has not been completed evaluation yet. Otherwise no DLT was observed. Conclusions: The radiation dose of 74 Gy in 37 fractions with concurrent cisplatin and S-1 seemed to be tolerable and was judged to be the RD. This study is still open to accrue another six patients to confirm the safety of the RD. No significant financial relationships to disclose.