Phase 2 study of high-dose proton therapy with concurrent chemotherapy for unresectable stage III nonsmall cell lung cancer

BACKGROUND: The authors sought to improve the toxicity of conventional concurrent chemoradiation therapy for stage III nonsmall cell lung cancer (NSCLC) by using proton-beam therapy to escalate the radiation dose to the tumor. They report early results of a phase 2 study of high-dose proton therapy and concurrent chemotherapy in terms of toxicity, failure patterns, and survival. METHODS: Forty-four patients with stage III NSCLC were treated with 74 grays (radiobiologic equivalent) proton therapy with weekly carboplatin (area under the curve, 2 U) and paclitaxel (50 mg/m²). Disease was staged with positron emission tomography/computed tomography (CT), and treatments were simulated with 4-dimensional (4D) CT to account for tumor motion. Protons were delivered as passively scattered beams, and treatment simulation was repeated during the treatment process to determine the need for adaptive replanning. RESULTS: Median follow-up time was 19.7 months (range, 6.1-44.4 months), and median overall survival time was 29.4 months. No patient experienced grade 4 or 5 proton-related adverse events. The most common nonhematologic grade 3 toxicities were dermatitis (n = 5), esophagitis (n = 5), and pneumonitis (n = 1). Nine (20.5%) patients experienced local disease recurrence, but only 4 (9.1%) had isolated local failure. Four (9.1%) patients had regional lymph node recurrence, but only 1 (2.3%) had isolated regional recurrence. Nineteen (43.2%) patients developed distant metastasis. The overall survival and progression-free survival rates were 86% and 63% at 1 year. CONCLUSIONS: Concurrent high-dose proton therapy and chemotherapy are well tolerated, and the median survival time of 29.4 months is encouraging for unresectable stage III NSCLC. Cancer 2011;. © 2011 American Cancer Society Standard therapy for stage III nonsmall cell lung cancer, concurrent chemoradiation therapy with photon (x-ray-based) therapy, is associated with significant toxicity and produces suboptimal local control. The authors found that concurrent chemotherapy and high-dose proton beam therapy was less toxic than conventional photon-based treatments and produced a total local failure rate of 20.5%.