Evidence Hub

Impact of Ethnic Differences and HER2 Protein Expression on the Age at Breast Cancer Diagnosis: A Mixed Methods Study

Karutjaiva MS, Aboua YG, Omoruyi BE, Shafodino F, Chambuso R, Mwapagha LM, Okudoh VI

Cancer management and research, 2026

1,953 participants

Abstract

Purpose: Despite advances in breast cancer (BC) research, a significant research gap remains in understanding the interplay of ethnicity, Human Epidermal Growth Factor Receptor 2 (HER2) protein expression and age at BC diagnosis, particularly in underrepresented minority populations from Africa. We analyzed variations in HER2 protein expression and ethnic differences in age at BC diagnosis across indigenous Namibian and American women diagnosed with BC.

Methods: Using a mixed methods study, we analyzed case series cohort from 1,953 women all diagnosed with invasive BC, including 98 indigenous Namibian women and 1855 American women retrieved from the cBioPortal database. HER2 positivity rate was obtained by staining breast tissue biopsies and quantifying HER2 protein expression, with this study accessing the data retrospectively. We stratified participants by ethnicity and compared age at BC diagnosis and HER2 status to elucidate disparities. Chi-square test for proportions, t-test for independence and the cumulative probability analysis curves were used for statistical analysis. A p-value of <0.05 was considered significant.

Results: Indigenous Namibian women were diagnosed with BC significantly with a younger age compared to American women (White, p<0.0001, and African American p=0.0035). In a logistic regression analysis, African American women with BC had significantly lower odds of HER2-positive status compared to White women (OR = 0.52, p < 0.001). The cumulative…

How strong is the evidence?

Evidence Hub reads this as a case series, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health. Reported size: 1,953 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free