Breast cancer (BC) is the main cause of cancer-related death for women worldwide. While the incidence of disease is still higher in high income countries, lower and middle income countries have a proportionally higher mortality burden and account for almost half the deaths due to the disease globally. In Brazil, BC is the most common cancer in women, with mortality rates that almost equate those in the US. BC mortality has also been increasing steadily and most women are diagnosed with late stage disease greatly lowering their chances of survival. Data suggests that Black and Brown women suffer from higher excess disease mortality even when extent of disease, year of diagnosis, age and socioeconomic status are considered, highlighting a clear racial BC disparity. Less is known about the distribution of aggressive BC subtypes such as triple negative breast cancer (TNBC) in the Brazilian population in relation to race. Data suggests that TNBC is more common in the northeast of the country where the Afro-Brazilian population is larger. To expand our knowledge, we explore the presence of TNBC among women of different races diagnosed with BC and also its potential association with other variables. We conducted analysis on women that attended the Instituto Nacional do Câncer Hospital in Rio de Janeiro between the years 2016 and 2017, for which more complete data was available. We extracted subtype information from their pathology reports and used the Registros Hospitalares de Câncer (RHC) database to collect data on demographic/lifestyle factors such as age, race, education, alcohol and tobacco use, and disease stage at time of diagnosis. We conducted our analysis on 243 women with full records on all variables selected using multivariate logistic regression analysis. We found a significant difference in the proportion of TNBC by race, 41.2% of TNBC were found in Black women, while only 23.5% and 35.3% of the TNBC tumors were found in Brown and White women, respectively (p=0.028). We also found that TNBC was diagnosed in this cohort at a later stage than other subtypes. TNBC is diagnosed at a later clinical (III and IV) and pathological stage (3), while other subtypes tend to be diagnosed earlier at stages I/II or 1/2a. 47% of women with TNBC are diagnosed with stage 3a and 3b, while only 13.4% of women with other cancer are diagnosed at these stages (p=0.024). Similarly, of all diagnoses made at stage III and IV, 47.1% were TNBC and 14.7% were of other tumors (p=0.001). When adjusted for age and clinical stage, being Black was still significantly associated with being diagnosed with TNBC (β=1.57, 95% Confidence Interval 1.67-13.75, p=0.004). Interestingly, similar associations between race and TNBC diagnosis were not observed in women that self identified as Brown. These preliminary results add to our knowledge of the importance of considering subtype when analyzing race/ethnicity in association to BC outcomes. In future work, we will expand our analysis to other clinical variables and use larger samples to better understand these associations.
Citation Format: Lissette Delgado-Cruzata, Flavia Carvalho, Diego Gomes, Tatiana Simão, Jennifer Vieira, Rachele Grazzioti, Sheila Coelho. Racial disparities in triple negative breast cancer in urban Brazilian women [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C073.
