Abstract C71: Racial and socioeconomic disparities in staging magnetic resonance imaging (MRI) utilization for prostate cancer (PCa) patients undergoing radiotherapy
Authors: Ajayi Ayobami , Chapman Christina , Both Stefan , Deville Curtiland 
Published: May 2016

Purpose: To determine whether racial disparities exist within socioeconomic classes in MRI utilization and imaging characteristics for PCa patients undergoing radiotherapy.

Methods: An institutional database at the University of Pennsylvania identified 715 non-metastatic PCa patients treated with proton and/or intensity modulated radiotherapy from 2005-2013 with pre-treatment pelvic MRI (T2 weighted, diffusion weighted, and/or dynamic contrast-enhanced sequences, 91% with endorectal coil). MRI utilization for staging was compared in 1) high socioeconomic status (SES) vs. low SES (defined as geocoded census tract &gt; 20% below the poverty level) Whites, 2) high SES vs. low SES Blacks, 3) Whites vs. Blacks within high SES, and 4) Whites vs. Blacks within low SES, overall and stratified by risk group, using Fishers exact test for categorical variables (p&lt;0.05 significant).

Results: In this cohort, 431 were identified as white (60%) and 236 as black (33%). 523 were classified as high SES (73%) and 191 as low SES (27%). Median age (67) or Gleason score did not differ significantly for Whites vs. Blacks or for high SES vs. low SES. Mean pre-RT PSA did, 7.8 ± 10.8 vs. 13.5 ± 20.2 (p&lt;0.001) in Whites vs. Blacks and 8.1 ± 12.2 vs. 14.0 ± 19.3 (p&lt;0.001) in high SES vs. low SES. Blacks were more likely to be low SES (69%) than Whites (5%), p&lt;0.001.

546 (77%) of 715 total patients received baseline MRI, including High SES Whites (332/411; 81%), Low SES Whites (14/20; 70%), High SES Blacks (51/74; 69%), Low SES Blacks (108/162; 67%), other (non-white and non-black, all SES) (41/48; 85%). Within the low risk group, 190 (76%) of 250 total low risk patients received baseline MRI, including High SES Whites (138/161; 86%), Low SES Whites (5/7; 71%), High SES Blacks (18/28; 64%), Low SES Blacks (19/38; 50%), other (10/16; 63%).

Overall, Blacks were less likely to receive staging MRI (67%) than Whites (80%) p&lt;0.001. This disparity was entirely limited to the low risk group: Blacks (56%) vs. Whites (85%), p&lt;0.001. Additionally, low SES were less likely to receive staging MRI (68%) than high SES (80%), p=0.001. When separating by race and SES, high SES Blacks were less likely to receive staging MRI (69%) than high SES Whites (81%), p=0.029, while Whites were no different: low SES (%) vs high SES (%) p&gt;0.05. Within the low-risk group specifically, high SES Blacks were more likely to receive staging MRI (24%) than low SES Blacks (12%), p=0.02, while there was no difference in staging MRI utilization between high SES and low SES Whites in the low-risk group.

Conclusions: In this urban, academic center cohort, Black PCa patients were significantly less likely to undergo staging MRI than Whites. Among patients with similar high SES, Blacks were still less likely to undergo staging MRI than Whites. Furthermore, while low SES patients were less likely to undergo staging MRI than high SES patients, this difference was driven entirely by the difference seen in Blacks because on subset analysis, there was no difference in low SES Whites compared to high SES Whites but there was a significant difference in low SES Blacks compared high SES Blacks, specifically in the low risk group. Further research should investigate these differences in MRI utilization, given the known disproportionate burden of prostate cancer morbidity and mortality in Blacks.

Citation Format: Ayobami Ajayi, Christina Chapman, Stefan Both, Curtiland Deville. Racial and socioeconomic disparities in staging magnetic resonance imaging (MRI) utilization for prostate cancer (PCa) patients undergoing radiotherapy. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr C71.