Efficacy and cost of high-frequency IGRT in elderly stage III non-small-cell lung cancer patients

BACKGROUND: High-frequency image-guided radiotherapy (hfIGRT) is ubiquitous but its benefits are unproven. We examined the cost effectiveness of hfIGRT in stage III non-small-cell lung cancer (NSCLC). METHODS: We selected stage III NSCLC patients ≥66 years old who received definitive radiation therapy from the Surveillance, Epidemiology, and End-Results-Medicare database. Patients were stratified by use of hfIGRT using Medicare claims. Predictors for hfIGRT were calculated using a logistic model. The impact of hfIGRT on lung toxicity free survival (LTFS), esophageal toxicity free survival (ETFS), cancer-specific survival (CSS), overall survival (OS), and cost of treatment was calculated using Cox regressions, propensity score matching, and bootstrap methods. RESULTS: Of the 4,430 patients in our cohort, 963 (22%) received hfIGRT and 3,468 (78%) did not. By 2011, 49% of patients were receiving hfIGRT. Predictors of hfIGRT use included treatment with intensity-modulated radiotherapy (IMRT) (OR = 7.5, p < 0.01), recent diagnosis (OR = 51 in 2011 versus 2006, p < 0.01), and residence in regions where the Medicare intermediary allowed IMRT (OR = 1.50, p < 0.01). hfIGRT had no impact on LTFS (HR 0.97; 95% CI 0.86–1.09), ETFS (HR 1.05; 95% CI 0.93–1.18), CSS (HR 0.94; 95% CI 0.84–1.04), or OS (HR 0.95; 95% CI 0.87–1.04). Mean radiotherapy and total medical costs six months after diagnosis were $17,330 versus $15,024 (p < 0.01) and $71,569 versus $69,693 (p = 0.49), respectively. CONCLUSION: hfIGRT did not affect clinical outcomes in elderly patients with stage III NSCLC but did increase radiation cost. hfIGRT deserves further scrutiny through a randomized controlled trial.