Abstract C106: Racial/ethnic disparities in inflammatory breast cancer survival in the Michigan Cancer Surveillance Program

Abstract Background: Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer, largely due to its strong metastatic potential. The lack of a standard case definition for IBC over time, coupled with the fact that IBC is a relatively rare disease, has severely limited our understanding of the disease. While racial disparities in IBC incidence are fairly well documented, with black women having significantly higher IBC rates compared to white women, less is known about whether IBC prognosis differs by race/ethnicity. Therefore, the objective of this study was to utilize a comprehensive case definition of IBC to assess racial/ethnic disparities in survival in the Michigan Cancer Surveillance Program (MCSP) from 1998 to 2014. Methods: Using a comprehensive case definition of IBC, 1,324 IBC patients were identified from women diagnosed with invasive breast cancer in the MCSP between 1998 and 2014 with information on survival time and race/ethnicity (non-Hispanic Black (NHB)=227; non-Hispanic White (NHW)=984; Hispanic =86; other =27). We examined the frequency and percentage of breast cancer cases coded to the various IBC codes in the MCSP registry over the study period. We used age-adjusted and multivariable Cox proportional hazard regression models with age as the underlying time metric to estimate hazard ratios (HR) and 95% confidence interval (CI) for associations of race/ethnicity with all-cause mortality, using NHW women as the reference group. Results: The percentage of all breast cancer cases defined as IBC in the MCSP registry differs considerably across registry codes from 0.03% to 1.2%. We observed significantly higher risk of death among NHB compared with NHW (HR (95% CI), 1.21 (1.01-1.45)), while no significant survival differences were observed between NHW and Hispanics or other racial/ethnic minorities. Conclusions: A comprehensive case definition should be utilized to avoid underestimation of IBC and to better understand this aggressive disease. Further research is needed to identify underlying causes and develop effective interventions to reduce survival disparities in IBC. Citation Format: Abdi T. Gudina, Glenn Copeland, Amr Soliman, Kelly A. Hirko. Racial/ethnic disparities in inflammatory breast cancer survival in the Michigan Cancer Surveillance Program [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C106.