Comparison of rates of vaginal brachytherapy vs. external beam radiation post-hysterectomy for endometrial cancer patients in rural vs. urban settings (459)

Abstract

<b>Objectives:</b> The GOG-99 trial published in 2004 demonstrated that patients with high-intermediate risk endometrial cancer benefit from adjuvant external beam radiation therapy (EBRT) post-hysterectomy to decrease the risk of recurrence. The PORTEC-2 trial was then published in 2010, which was an open-label, non-inferiority randomized control trial that compared vaginal brachytherapy (VBT) to EBRT for patients with high-intermediate risk endometrial cancer. This trial demonstrated non-inferiority of VBT compared to EBRT with no significant difference in vaginal or locoregional recurrence, overall survival, and disease-free survival. However, it did show a significant decrease in grade 1-2 gastrointestinal toxicities in the VBT group. VBT is now the standard of care given its decreased toxicity but is also notably less time-consuming for patients. Our objective was to identify if there was a difference in the administration of VBT versus EBRT for endometrial cancer patients post-hysterectomy in rural versus urban locations. <b>Methods:</b> This is a retrospective cohort study based on the SEER 18 dataset of the US National Cancer Institute. Women with localized endometrial cancer post-hysterectomy were included in this study. The SEER dataset defines a localized tumor as a tumor confined to the organ of origin without extending beyond the primary organ. Data were collected from 2011 to 2018, given that PORTEC-2 was published in 2010. Urban versus rural population was defined by the rural-urban continuum codes. Women were excluded if they received both VBT and EBRT or if a rural-urban continuum code was not provided. Statistical analysis was completed with relative risk and confidence interval calculation. <b>Results:</b> In total, 10,840 women were included. There were 9813 women identified in metropolitan counties; 22% (<i>n</i>=2136) received EBRT post-hysterectomy for localized endometrial cancer, whereas 78% underwent VBT. There were 1027 women identified in nonmetropolitan counties, 22% (<i>n</i>=230) received EBRT and 78% (<i>n</i>=797) received VBT. When comparing metropolitan versus nonmetropolitan counties, there was no statistical difference between rates of EBRT versus VBT, with a relative risk of 1.16 (95% CI: 0.91-1.16, p=0.64). There were 125 women identified in completely rural counties, 21% (<i>n</i>=26) received EBRT and 79% (<i>n</i>=99) received VBT. There was no statistical difference in rates of radiation therapy between completely rural and metropolitan counties, with a relative risk of 0.95 (95% CI: 0.67-1.34, p=0.77). <b>Conclusions:</b> Living in a nonmetropolitan county or even a completely rural county was not associated with a difference in receiving EBRT versus VBT in patients with localized endometrial cancer status post-hysterectomy compared to rates in metropolitan counties. It could be inferred that even though rural counties may have fewer medical resources, patients are still receiving the standard of care in regard to radiation therapy for endometrial cancer.