Tumor-Infiltrating Lymphocytes in African Americans and European Americans With Triple-Negative Breast Cancer


Key Points

  • The presence of tumor-infiltrating lymphocytes (TILs) varied significantly in the tumors of African American and European American women with triple-negative breast cancer, with African American patients harboring more tumor-infiltrating lymphocytes.
  • High peripheral TILs were associated with better 10-year survival among early-stage African American patients.
  • The disparity in tumor microenvironment suggests that TILs may serve as a prognostic biomarker to stratify African American patients with early-stage triple-negative breast cancer into high- and low-risk groups to allow for the optimization of treatment paths.

Triple-negative breast cancer is a highly aggressive breast cancer that lacks hormone receptors and overexpression of human epidermal growth factor receptor 2 (HER2/neu), and, therefore, there are no targeted treatments available for the cancer. Triple-negative breast cancer afflicts African American women at a rate two to three times higher than European American women and is often diagnosed at a later stage, resulting in poorer outcomes for these patients, according to a study by Wright et al.

The study investigated the distinctions in inherent tumor biology between racially distinct triple-negative breast cancers and found that the presence of tumor-infiltrating lymphocytes (TILs) varied significantly, with African American patients harboring more TILs than European American patients. The study findings suggest that TILs might be a useful prognostic biomarker and allow for optimizing treatment options. The study (Abstract B40) was presented at the 10th American Association of Cancer Research Conference on The Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved on September 25–28 in Atlanta.

Study Methodology

The researchers tested resection samples from 121 African American patients and European American patients with triple-negative breast cancer who had received adjuvant chemotherapy at Emory University Hospital in Atlanta. They then compared the patients’ overall TIL count.

Study Findings

The researchers found a trend of more TILs among African American (n = 87) compared with European American (n = 34) patients (= .06). Among early stage (I–II) patients, they found that African Americans (n = 71) harbored significantly more TILs than European Americans (n = 32; = .019) but not among late stage (III–IV) patients (= .86). Among early-stage African American patients, more TILs negatively correlated with younger age at diagnosis (= .03) and carcinoma in situ (= .06) and positively correlated with intramammary lymph node involvement (= .002), tubule formation (= .07), and Nottingham grade (= .08).

Furthermore, TILs correlated negatively with AR expression (= .04) and positively with BRCA1-associated protein (= .02) and programmed cell death protein 1 (= .0001) expression. TILs also correlated positively with 5- and 10-year survival more strongly among early-stage African American patients (< .05). Among adjuvant chemotherapy-treated early-stage patients, TILs were also associated with better 5- and 10-year survival among African Americans than European Americans (< .05).

The researchers’ findings suggest that TILs may serve as a prognostic biomarker that can stratify early-stage African American patients with triple-negative breast cancer into high- and low-risk groups to allow for the optimization of treatment paths.

“Further investigation into disparities in the immune landscape or tumor microenvironment among [African American] and [European American triple-negative breast cancers] may yield promising new biomarkers and therapeutic targets for [triple-negative breast cancer] patients of African ancestry,” concluded the researchers.

In a statement, lead author of the study, Nikita Wright, BS, a PhD candidate at Georgia State University in Atlanta, said: “These findings uncover a previously unrecognized disparity in the tumor microenvironment between African American and European American [triple-negative breast cancer] patients. If confirmed, these findings suggest TILs can be used to predict patient prognosis in the early stages of disease for African American [triple-negative breast cancer] patients. This insight is clinically actionable and of great potential value for guiding treatment of these patients so that their survival may be improved.”

The study was funded by the National Cancer Institute.

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