GSOR15 Presentation Time: 11:40 AM: Underutilization of Brachytherapy: A Retrospective State Level Analysis of Brachytherapy Delivery in Locally Advanced Cervical Cancer

Abstract

<h3>Purpose</h3> The standard of care for locally advanced cervical cancer is concurrent chemotherapy and external beam radiation therapy (EBRT) followed by a brachytherapy boost. Decreased rate of brachytherapy in cervical cancer patients has shown a declining survival for these patients. This study aims to characterize the utilization of brachytherapy in Oregon in order to better understand how care delivery can be improved. <h3>Materials and Methods</h3> The Oregon State Cancer Registry database was used to identify patients diagnosed with FIGO 2008 Stage IB2-IVB cervical cancer between 2007 and 2016. Patients who received initial EBRT were categorized by whether they received brachytherapy boost or not. Age at diagnosis, county, rural/urban status of the county, race/ethnicity, and insurance payer were studied using multivariable logistic regression to identify possible underserved populations. Survival data was compared using a Cox proportional hazard survival model. Changes in brachytherapy use over time were also examined by grouping patients by year of diagnosis and comparing the rates of brachytherapy utilization over the duration of the study. <h3>Results</h3> 401 patients who received primary EBRT for FIGO stage IB2-IVB cervical cancer were identified in the 10-year span. Breakdown by stage is: 16% stage IB2, 23.9% stage II, 37.4% stage III, and 22.7% stage IV. Of those, 154 (38.4%) received brachytherapy boost treatment, 75 (18.7%) received a different boost modality, and 172 (42.9%) received no boost. Stage IV (p=0.001) and uninsured patients (p=0.04) were significantly less likely to receive brachytherapy. Older age was also associated with decreased brachytherapy usage, as each additional year of life correlated with a decreased likelihood of brachytherapy receipt of 1.8% (p=0.04). Native American and Pacific Islander patients were the only group significantly more likely to receive brachytherapy (p=0.003). There was no significant difference in the rate of brachytherapy boost based on urban/rural status of the county (p=0.63 to 0.69), other racial/ethnic categories (p=0.66 to 0.80), or among the other stages (p=0.45 to 0.63). In Cox proportional hazard survival analysis, patients that received brachytherapy showed a 42% reduction in risk of cancer specific mortality, though this did not reach the level of statistical significance (p=0.057). In terms of brachytherapy utilization by year, no definitive trend was shown. Yearly rates varied from 25% to 52%, with a dip in utilization in 2013 and 2014 at around 30% before a jump in utilization in 2015 and 2016 to around 50%. <h3>Conclusions</h3> The brachytherapy boost rates among locally advanced cervical cancer patients were 38.4%. Though not statistically significant, a reduction in cancer specific mortality in patients receiving brachytherapy by 42% was seen. Older patients, stage IV patients, and uninsured patients were less likely to receive brachytherapy. Given the low overall brachytherapy usage, these data may indicate barriers to access and delivery of brachytherapy care. The increased brachytherapy use in the American Indian and Pacific Islander patient population should be further studied to identify facilitators to treatment completion and potentially extrapolate to other groups.