Treatment with Intensity-Modulated Radiation Therapy (IMRT) and Chemotherapy in Advanced Inoperable Non-Small Cell Lung Cancer (NSCLC): Toxicity, Survival and Patterns of Failure in Relation to Treatment with High and Low Radiation Dose

Purpose: To investigate the toxicity, survival and patterns of failure in patients with advanced lung cancer treated with intensity modulated radiation therapy (IMRT) and chemotherapy. Methods and Materials: Retrospective chart review of 68 total patients: 46 academic and 22 community center. Endpoints: Grade ≥ 3 pneumonitis, Grade ≥ 2 esophagitis, local, regional and distant failure, progression-free survival (PFS) and overall survival (OS). Results: For the academic center patients, median follow-up was 19.2 months. Esophagitis: 0% Grade 3, 35% Grade 2, no significant difference between dose bins: <70 Gy vs. 70 Gy, 25% vs. 45% (p = 0.22), <66 Gy vs. 66 - 70 Gy, 28% vs. 39% (p = 0.53). Lung dose metrics and PTV size were not associated with Grade ≥ 3 pneumonitis. Esophageal V35, V50, and mean dose but not PTV size was associated with Grade 2 esophagitis. 1 year local, regional and distant failure = 6.5%, 6.5%, and 30.4%. No endpoint differences were seen between dose bins, though patients with smaller PTVs treated with 70 Gy did demonstrate improved OS (ns) when compared to those treated with <70 Gy. Community Center: Median follow-up 6.2 months with 15% Grade 2 esophagitis, no Grade 3 esophagitis. Two patients (9%) experienced Grade ≥ 3 pneumonitis. Conclusions: IMRT chemoradiation was well tolerated in a population with advanced NSCLC both in the academic and community settings. Severe pneumonitis rates were low and comparable to other series using IMRT and chemotherapy. Esophagitis was mild and associated with V35, V50 and mean dose. No significant benefit was seen for higher doses regarding survival, local, regional or distant control despite that higher dose bins had smaller tumors. Though not statistically significant, we did find a trend toward worse OS for <70 Gy when the PTV was less than the median PTV.