Environmental Risk Factors and Racial Inequities in TNBC Diagnosis Stages: A Bayesian Mediation Study in Louisiana

Triple-negative breast cancer (TNBC) has a higher recurrence rate and poorer overall mortality than other molecular subtypes in U.S. Studies have shown that African American (AA) women are genetically more likely to develop advanced TNBC than Caucasian American (CA) women. In Louisiana (LA), there were 3,790 TNBC cases from 2010 to 2017, of which 1,861 (49.1%) were AA versus 1,900 (50.1%) were CA. However, 32.8% of the LA population were AA and 62.8% were CA. Notably, 43.5% of the AA patients were diagnosed with regional or distant metastasis, compared with 36.6% of CA patients. Thus, TNBC diagnosis stage represents a significant challenge to racial health disparities in LA.

Our research is based on data collected by the Louisiana Tumor Registry (LTR) from 2010-2017. In addition to the routinely collected standard data, LTR connected related variables with U.S. census tract level environmental factors from National Scale Air Toxics Assessment (NATA) along with the environmental justice indices (EJI). A total of 3,225 adult female TNBC patients were included in the dataset. Among them, 1,675 (51.9%) were AA and 1,550 (48.1%) were CA. We used the Bayesian mediation analysis method to identify environmental risk factors and quantify their effects that explain the racial disparities in stage at diagnosis among TNBC patients in Louisiana.

There is significant association between race and stage at diagnosis (p-value < 0.001). The disparity was partially explained using the collected mediators. The significant mediators included patient's age at diagnosis (25.89%), insurance (4.71%), poverty index (26.16%) and environmental chemical Naphthalene (8.38%).

In LA, a high proportion of Black residents live in cancer ally. This exposes them to high toxic emission that contains carcinogens like Naphthalene. Early diagnosis, improving access to health insurance, reducing poverty-related barriers, reducing exposure to Naphthalene can help with early detection of TNBC.

Breast Cancer Diagnosis Stage

Racial Disparity

Bayesian Mediation

Environmental Risks

Naphthalin

TNBC 

Practice and Applications

Symposium on Data Science and Statistics (SDSS) 2025