Black Population May Have Worse Breast Cancer Outcomes Vs White Population

"In our study, [non-Hispanic Black patients] experienced disproportional burden of poor breast cancer outcomes compared to [non-Hispanic White patients] diagnosed with IBC," according to the authors of a study published in Breast Cancer Research and Treatment.

Non-Hispanic Black patients with inflammatory breast cancer (IBC) are more likely to die of their disease than their non-Hispanic White counterparts despite similar odds of receiving treatment, according to findings from a retrospective study published in Breast Cancer Research and Treatment.

After adjustment for sociodemographic, clinicopathological, and treatment covariables, Black patients had similar odds of receiving surgery (odds ratio [OR], 0.75; 95% CI, 0.52-1.09) and radical mastectomy (OR, 0.85; 95% CI, 0.64-1.12) as White patients. The incidence of radiotherapy use was 57% vs 62% (P = .07), the incidence of chemotherapy use was 88% vs 87% (P = .66), and the incidence of trimodal therapy use was 42% vs 46% (P = .20) among Black vs White patients, respectively. There was no significant difference between the groups in the odds of receiving radiation (OR, 0.86; 95% CI, 0.63-1.18), chemotherapy (OR, 0.93; 95% CI, 0.58-1.51) or trimodal therapy (OR, 0.87; 95% CI, 0.67-1.13).

Nonetheless, the median overall survival (OS) was 40 months among Black patients and 81 months among their White counterparts (P <.0001) after a median follow-up of 39 months. The OS rate at 5 years was 39% vs 57%, respectively. After adjustment for covariables, Black patients experienced worse OS than their White counterparts (HR, 1.34; 95% CI, 1.13-1.59; P <.001).

“In our study, [non-Hispanic Black patients] experienced disproportional burden of poor breast cancer outcomes compared to [non-Hispanic White patients] diagnosed with IBC. We demonstrate that the odds of receiving chemotherapy, radiation therapy, surgery, radical mastectomy, or trimodal therapy were similar for [non-Hispanic Black] and [non-Hispanic White patients],” the investigators wrote.

Investigators derived these findings from an analysis of 1652 White and 371 Black patients in the Surveillance, Epidemiology, and End Results (SEER) database, with a follow-up cutoff date of December 31, 2018.

Black patients had a mean age of 55 years compared with 59 years among their White counterparts (P <.001). In sum, 65% of Black patients and 43% of White patients were unmarried (P <.001). Black patients were more likely to live in regions at the lowest quintile of socioeconomic status and country level (42%) than White patients (11%; P <.001); the same was true at the state level (39% vs 11%; P <.001).

Black patients were more likely to have triple-negative breast cancer (30%) than White patients (23%), although hormone receptor (HR)­–positive/HER2-negative (32% vs 36%) and HR-positive/HER2-positive (15% vs 18%) disease was less common in Black vs White patients (P = .035). Grade 3 or 4 tumors were equally likely in both groups (58% vs 58%), and ductal histology was most common in both (69% vs 66%).

Notably, an increased risk of death from breast cancer among Black patients was observed in patients younger than 65 years (sub-distribution HR (sHR), 1.36; 95% CI, 1.09-1.70) but not in their older counterparts. There was an increased risk of death in those who underwent surgery compared with those who did not (sHR, 1.54; 95% CI, 1.21-1.94), and in those who underwent radiation therapy (sHR, 1.56; 95% CI, 1.19-2.04).

“Independent of breast cancer subtype, grade, and stage; breast cancer arising at young age seems to be biologically distinct, with higher expression of RANK-ligand, c-kit, mammary stem cell, and luminal progenitors, and BRCA1 mutation signatures,” the investigators wrote. “The difference in IBC outcomes among non-Hispanic Black patients who received surgery or radiation could be due to intrinsic tumor resistance to IBC treatment, unmeasured differences in tumor biology, differences in medical comorbidities that could affect radiation dose or schedule, or unmeasured treatment and/or socioeconomic factors.”

Despite the large sample size, investigators noted that these retrospective findings are limited by the potential of unmeasured confounders. Moreover, some details of chemotherapy and radiation treatment, such as regimen, dose, delays, and toxicities, are not provided by the SEER database.

“Future studies that focus on tumor microenvironment, tumor biology, treatment efficacy, and access to care in non-Hispanic Black [patients] with IBC could advance understanding of the drivers of IBC outcome disparities and complement a deeper understanding of socioeconomic determinants,” the investigators concluded.

Reference

Carbajal-Ochoa WH, Johnson D, Alvarez A, Bernal AM, Anampa JD. Racial disparities in treatment and outcomes between non-Hispanic Black and non-Hispanic White women with nonmetastatic inflammatory breast cancer. Breast Cancer Res Treat. Published online July 13, 2023. doi:10.1007/s10549-023-07018-7