Correlation of dosimetric and clinical factors with the development of esophagitis and radiation pneumonitis in patients with limited-stage small-cell lung carcinoma.

BACKGROUND: The purpose of the study was to correlate clinical and dosimetric factors with the development of esophagitis and radiation pneumonitis in patients with limited-stage small-cell lung carcinoma (LS SCLC). PATIENTS AND METHODS: One hundred eighteen patients who received curative intent chemoradiotherapy for LS SCLC and had electronically archived radiation treatment plans were included. The medical charts were reviewed for clinical data. The treatment plan was reviewed for critical structure delineation and dose delivered. Treatment planning data were analyzed using Computational Environment for Radiotherapy Research (V3.3). Dosimetric parameters were correlated with the risk of toxicity using Spearman rank correlation. RESULTS: Radiotherapy dose was 40 Gy in 15 fractions (fx) (n = 80) and 45 Gy in 30 fractions twice per day (n = 38). The 6-month cumulative incidence of Grade ≥ 2 radiation pneumonitis was 6.5% and 7.9% for the 40 Gy/15 fx and 45 Gy/30 fx groups, respectively (P = .40). The 3-month cumulative incidence of Grade 3 esophagitis was 7.5% and 13.2% for the 40 Gy/15 fx and 45 Gy/30 fx groups, respectively (P = .31). Grade ≥ 3 pneumonitis was correlated with volume of lung receiving 20 Gy (V20) and mean lung dose. Grade ≥ 3 esophagitis was correlated with mean esophagus dose and minimum dose to the hottest 45% of the esophagus (D45). CONCLUSION: Mean lung dose and V20 were significant predictors of radiation pneumonitis in LS SCLC. Mean esophageal dose and D45 were significant predictors of esophagitis. These 2 treatment schedules have similar toxicity profiles.