Racial/ethnic disparities in inflammatory breast cancer survival in the Michigan Cancer Surveillance Program.

PURPOSE: While racial disparities in inflammatory breast cancer (IBC) incidence are fairly well documented, with black women having significantly higher rates compared to white women; less is known about whether IBC prognosis differs by race/ethnicity. Therefore, the objective of this study was to assess racial/ethnic disparities in survival among women diagnosed with IBC in the Michigan Cancer Surveillance Program (MCSP) from 1998 to 2014.

METHODS: 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 to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of race/ethnicity with all-cause mortality.

RESULTS: Using a comprehensive case definition of IBC, 1324 IBC patients were identified from women diagnosed with invasive breast cancer in the MCSP [Non-Hispanic Black (NHB) = 227; Non-Hispanic White (NHW) = 984; Hispanic = 86; other = 27]. The percentage of all breast cancer cases defined as IBC in the MCSP registry differs considerably across registry codes from 0.02 to 1.1%. 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 IBC survival disparities between NHB and NHW women.