Background: A phase I/II study was first conducted for the treatment of stage I non-small cell lung cancer (NSCLC) from 1994 to 1999 to determine the optimal dose. On the basis on the results, a phase II study using a regimen of four fractions during 1 week was performed. The purpose of the present study was to determine the local control and 5-year survival rates.
Methods: From December 2000 to November 2003, 79 patients with 80 primary lesions were treated. Using a fixed dose of 52.8 GyE for stage IA NSCLC and 60.0 GyE for stage IB NSCLC in four fractions during 1 week, the primary tumors were irradiated with carbon beams alone. The average age of the patients was 74.8 years. Sixty-two (78.5%) of these patients were medically inoperable. Local control and survival were determined using the Kaplan-Meier method. The data were statistically processed using the log-rank test.
Results: All patients were observed for a minimum of 3 years or until death, with a median follow-up time of 38.6 months, ranging from 2.5 to 72.2 months. The local control rate for all patients was 90% (T1: 98%, T2: 80%). The patients' 5-year lung cancer-specific survival rate was 68% (IA: 87%, IB: 42%). The overall survival was 45% (IA: 62%, IB: 25%). Half of the deaths were attributable to intercurrent diseases. No toxic reactions in the lung greater than grade 3 were detected.
Conclusion: Carbon ion beam radiotherapy with a regimen of four fractions during 1 week has been proven as a valid alternative to surgery for stage I NSCLC and to offer particular benefits, especially for elderly and inoperable patients.