The impact of IMRT on hospitalization outcomes in the SEER-Medicare population with anal squamous cell carcinoma

Publication date: Available online 7 January 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Erqi L. Pollom, Guanying Wang, Jeremy P. Harris, Albert C. Koong, Eran Bendavid, Jay Bhattacharya, Daniel T. Chang
PurposeWe examined the impact of intensity-modulated radiotherapy (IMRT) on hospitalization rate in the SEER-Medicare population with anal squamous cell carcinoma (SCC).MethodsWe performed a retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. We identified patients with non-metastatic anal SCC diagnosed between 2001 and 2011 and treated with chemoradiotherapy. We assessed the relation between IMRT and first hospitalization using a multivariate competing risk model as well as instrumental variable analysis, using provider IMRT affinity as our instrument.ResultsOf the 1,165 patients included in our study, 458 (39%) received IMRT. IMRT use increased over time, and was associated more with regional and provider characteristics, rather than patient characteristics. The 3- and 6-month cumulative incidences of first hospitalization were 41.9% (95% CI 37.3-46.4) and 47.6% (95% 43.0-52.2), and 46.7% (95% CI 43.0-50.4) and 52.1% (95% CI 48.4-55.7) for the IMRT and non-IMRT cohorts, respectively. IMRT was associated with a decreased hazard of first hospitalization compared to 3-D radiation techniques (HR 0.70, 95% CI 0.58-0.84, p=0.0002). Instrumental variable analysis suggested an even greater reduction in hospitalizations with IMRT after controlling for unmeasured confounders. There was a trend toward improved overall survival with IMRT, with an adjusted hazard ratio of 0.77 (95% CI 0.59-1.00, p=0.05).ConclusionThe use of IMRT is associated with reduced hospitalizations in elderly patients with anal squamous cell carcinoma. Further work is warranted to understand the long-term health and cost impact of IMRT, particularly for patient subgroups most at risk of toxicity and hospitalization.



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