[Heavy ion therapy for non-small cell lung cancer]

Carbon beam radiation has well-balanced dual actions on cancer: efficient dose localization and potent biological anticancer effect due to high RBE (Relative Biological Effectiveness). Two phase I/II clinical studies on the carbon beam radiation treatment of inoperable stage I non-small cell lung cancer (NSCLC) were carried out in our institution from October 1996 to February 1999. The dose-limiting toxicity was found to be radiation pneumonia. In the first protocol, 47 patients received 18 fractions of increasing doses from 59.4 GyE by 10% over 6 weeks. The maximum tolerated dose was found to be 95.4 GyE, while the complete tumor control dose was 85.6 GyE. In the second protocol, 34 patients received 9 fractions of in creasing doses from 68.4 GyE by 5% over 3 weeks. The maximum tolerated dose was 79.2 GyE, and the complete tumor control dose was > 68.9 GyE. The 4-year survival rate estimated by the Kaplan-Meier method was 56% for patients receiving the first protocol. Because a higher local control rate was achieved in the second protocol, the 5-year survival rate is estimated to be higher and similar to that achieved after surgery. Another phase II clinical study in patients with stage INSCLC is ongoing. Heavy-particle radiotherapy is a new modality for the treatment of lung cancer which holds promise for the 21st century.