Proton-beam radiotherapy for early-stage lung cancer

Study objective: A prospective study was undertaken to assess the efficacy and toxicity of conformal proton-beam radiotherapy for early-stage, medical ly inoperable non-small cell lung cancer. Design: Eligible patients had clinical stage I to IIIa non-small cell lung cancer and mere not candidates for surgical resection for medical reasons o r because of patient refusal. Patients with adequate cardiopulmonary functi on received 45 Gy to the mediastinum and gross tumor volume with photons wi th a concurrent proton boost to the gross, tumor volume of an additional 28 .8 cobalt gray equivalents (CGE). Total tumor dose was 73.8 CGE given over 5 weeks. Patients with poor cardiopulmonary function received proton-beam r adiotherapy to the gross tumor volume only, with 51 CGE given in 10 fractio ns over a e-week period. Results: Thirty-seven patients were treated in the study from July 1994 to March 1998. Clinical staging of patients was as follows: stage I, 27 patien ts; stage II, 2 patients; and stage IIIa, 8 patients. Eighteen patients rec eived a combination of protons and x rays, while 19 patients received proto n-beam radiation only. Follow-up of evaluable patients ranged from 3 to 45 months, with a median of 14 months. Two patients in the proton and photon a rm developed pneumonitis that resolved with oral steroids; otherwise, no si gnificant toxicities were encountered. The actuarial disease-free survival at 2 years for the entire group was 63%; for stage I patients, disease-free survival at 2 years was 86%. Local disease control was 87%, Conclusion: Preliminary results from this study indicate that proton-beam r adiotherapy can be used safely in this group of patients. Disease-free surv ival and local control appear to be good and compare favorably with publish ed reports utilizing conventional photon irradiation.