Purpose/Objective(s): The clinical benefit of intensity-modulated (IMRT) compared to 3D conformal radiation (3D-RT) has not been wellestablished for locally advanced non-small cell lung cancer (NSCLC). We evaluated trends in use of IMRT for stage III lung NSCLC and compared survival and hospitalization outcomes. Materials/Methods: Using SEER-Medicare data, we identified use of IMRT or 3D-RT among 7061 Medicare beneficiaries diagnosed with stage III NSCLC from 2002-2009. Factors associated with use of IMRT versus 3D-RT were identified using multivariable logistic regression. Overall survival and number of hospital days within 90 days of radiation were analyzed using Cox proportional hazard and negative binomial regression models, respectively. Propensity score adjustment was used to control for clinical and demographic variables. Results: IMRT comprised an increasing proportion of conformal treatments for NSCLC, rising from 3.0% in 2002 to 26.8% in 2009. Patients treated at freestanding versus hospital-based facilities were twice as likely to receive IMRT (17.3% vs 9.5%, adj ORZ 2.0, p < 0.01). IMRT use varied by region, with higher rates in the South (12.8%, adj OR Z 1.13) and West (14.2%, adj ORZ 1.25), compared to theNortheast (9.9%, ref) andMidwest (9.1%, adjOR Z 0.88) (overall pZ 0.03) and in urban versus rural areas (12.5% vs 9.9%, adj OR Z 1.52, p < 0.01). Patients with more comorbidities were more likely to receive IMRT, 11.3% (ref) vs 11.7% (adj OR Z 1.03) vs 14.7% (adj OR Z 1.35) for modified Charlson score 0, 1, and 2+, respectively (overall pZ 0.03). We did not find a difference in IMRT use between stage IIIA and stage IIIB patients (11.8% vs 12.4%, adj OR Z 1.11, p Z 0.19). Patients receiving chemotherapy were more likely to receive IMRT (12.8% vs 10.4%, adj ORZ 1.24, p Z 0.02), though there was no difference in IMRT use among patients having surgery (11.4% vs 12.2%, adj ORZ 0.95, pZ 0.68). With propensity score adjustment, IMRTwas associatedwith greater overall survival (adj HRZ 0.91, pZ 0.03) compared to 3D-RT, though there was no difference in survival among patients receiving at least 25 fractions of radiation (adj HRZ 0.99, pZ 0.83). There was no significant difference in number of hospital days in the 90 days following radiation start (mean 5 days, adj HR Z 1.01, p Z 0.89). Conclusions: When radiation is used to treat locally advanced NSCLC, IMRT is increasingly preferred to 3D-RT. However, among patients receiving potentially curative radiation ( 25 fractions) there was no significant difference in overall survival or time spent hospitalized following treatment compared to 3D-RT. Author Disclosure: A.B. Chen: None. L. Li: None. A. Cronin: None. D. Schrag: None.
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