Carbon Ion Radiotherapy in Hypofraction Regimen for Stage I Non-Small Cell Lung Cancer

Abstract

From 1994 to 1999, we conducted a phase I/II clinical trial for stage I non-small cell lung cancer (NSCLC) by using carbon ion beams alone, demonstrating optimal doses of 90 GyE in 18 fractions over 6 weeks and 72 GyE in 9 fractions over 3 weeks for achieving more than 95% local control with minimal pulmonary damage. In the present study, the total dose was fixed at 72 GyE in 9 fractions over 3 weeks, and at 52.8 GyE for stage IA and 60 GyE for stage 1B in 4 fractions over 1 week. Following this schedule, we conducted a phase II clinical trial for stage I NSCLC from 1999 to 2003. Most targets were irradiated from four oblique directions. A respiratory-gated irradiation system was used for all sessions. Local control and survival were assessed by the Kaplan-Meier method. For statistical testing, the long-rank test was used.The local control rate for all patients was 91.5%, and those for T1 and T2 tumors were 96.3% and 84.7%, respectively. While there was significant difference (p=0.0156) in tumor control rate between T1 and T2, there was no significant difference (P=0.1516) between squamous and non-squamous. The five-year cause-specific survival rate was 67.0% (IA: 84.4, IB: 43.7), and overall survival was 45.3% (IA: 53.9, 1B: 34.2). No adverse effects greater than grade 3 occurred in the lung. Carbon beam radiotherapy, an excellent new modality in terms of high QOL and ADL, was proven to be a valid alternative to surgery for stage I cancer, especially for elderly and inoperable patients