Is the Oncotype DX (Genomic Health) test accurate in the African American population?

From the Guidelines

The accuracy of Oncotype DX testing in African American populations is limited due to underrepresentation in validation studies, and therefore, healthcare providers should exercise caution when interpreting results for African American patients. The Oncotype DX test is widely used to guide breast cancer treatment decisions by predicting recurrence risk and chemotherapy benefit, but most validation studies have included predominantly white patients with minimal African American representation 1. Some research suggests potential differences in test performance across racial groups, with concerns that the test might underestimate recurrence risk in African American women. This could lead to undertreatment if relied upon exclusively. Key considerations include:

• Limited representation of African American patients in validation studies
• Potential differences in test performance across racial groups
• Risk of underestimating recurrence risk in African American women
• Need for additional clinical factors in treatment decisions. Healthcare providers should consider this limitation when interpreting Oncotype DX results for African American patients and may need to incorporate additional clinical factors into treatment decisions, as suggested by the EGAPP Working Group's recommendations on the use of Oncotype DX tumor gene expression profiling to guide treatment decisions in patients with breast cancer 1. More research specifically validating genomic tests like Oncotype DX in diverse populations is needed to ensure equitable cancer care. Until more representative validation data becomes available, clinicians should consider the test as one of multiple factors in treatment planning for African American breast cancer patients.

From the Research

Accuracy of Oncotype DX Test in African American Population

• The accuracy of the Oncotype DX test in the African American population has been investigated in several studies 2, 3, 4, 5, 6.
• A study published in 2023 found that the Oncotype DX score thresholds for chemotherapy benefit varied by race, with African American women benefiting from chemotherapy at a higher score threshold (37.2) compared to white women (19.9) and Asian women (18.0) 2.
• Another study published in 2017 found no significant difference in Oncotype DX scores between African American and white women, but noted racial differences in Ki-67 expression 3.
• Studies have also reported disparities in the uptake of Oncotype DX testing among African American women compared to white women, with African American women being less likely to receive the test 4, 5.
• A 2021 study found that the Oncotype DX test had lower prognostic accuracy in African American women, with a higher risk of breast cancer-specific mortality compared to white women with similar recurrence scores 6.
• The evidence suggests that the Oncotype DX test may not be equally accurate or effective in the African American population, highlighting the need for further research and calibration of the test for diverse patient populations 2, 6.

Racial Disparities in Oncotype DX Testing

• Racial disparities in Oncotype DX testing have been reported, with African American women being less likely to receive the test compared to white women 4, 5.
• A study published in 2017 found that African American women were 46% less likely to receive Oncotype DX testing compared to non-African American women with node-positive breast cancer 5.
• Another study published in 2016 found no racial disparities in Oncotype DX testing among node-negative patients, but noted disparities among node-positive patients 5.
• The disparities in Oncotype DX testing may contribute to differences in breast cancer outcomes and treatment decisions among African American women compared to white women 4, 5, 6.

Prognostic Accuracy of Oncotype DX Test

• The prognostic accuracy of the Oncotype DX test has been found to be lower in African American women compared to white women 6.
• A 2021 study found that the Oncotype DX test had a C index of 0.656 for African American women, compared to 0.700 for white women, indicating lower prognostic accuracy in African American women 6.
• The lower prognostic accuracy of the Oncotype DX test in African American women may be due to differences in tumor biology, genetic expression, or other factors 6.
• Further research is needed to understand the factors contributing to the lower prognostic accuracy of the Oncotype DX test in African American women and to develop more effective and accurate tests for diverse patient populations 2, 6.