Co-morbidity index predicts for mortality after stereotactic body radiotherapy for medically inoperable early-stage non-small cell lung cancer

Purpose: To determine the prognostic role of co-morbidity in medically inoperable early-stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy (SBRT). Methods and materials: Between 2000 and 2007, 88 consecutive early-stage medically inoperable NSCLC patients were treated by linac-based SBRT. The dose was either 45 Gy or 67.5 Gy in three fractions prescribed to the isocenter. Baseline co-morbidities were retrospectively retrieved by consultation of a formal electronic registry of diagnoses as well as patients' charts. The age-adjusted Charlson Co-morbidity Index (CCI) was scored for each patient and subjected to univariate and multivariate analysis. Results: With a median follow-up of 44 months, the actuarial local control rate at 4 years was 89% while the median overall survival was 22 months. The median age-adjusted CCI score was 5. The age-adjusted CCI was a significant predictor of overall survival on both univariate (p = 0.002) and multivariate analysis (p = 0.011). Patients with an age-adjusted CCI score of 3 or less had a median survival of 41 months versus only 11 months for those scoring 6 or more. Conclusion: The number and seriousness of co-morbidities predict overall survival in medically inoperable early-stage NSCLC treated with SBRT. Because the determination of medical operability is frequently based on both objective measures and subjective clinical judgment, it is recommended that co-morbidity be formally indexed in all studies examining the outcomes of SBRT.