Residential Proximity to NPL Superfund Sites and High Particulate Matter Exposure is Associated with Increased Likelihood of Triple Negative Breast Cancer.

Triple negative breast cancer (TNBC) is associated with disadvantaged neighborhoods and at-risk groups. Less is known about how environmental exposures drive TNBC. This study assesses associations between Superfund site (SF) and poor air quality exposure with TNBC. A retrospective review was performed for stage I-IV breast cancer (BCa) patients treated between 2005-2018. SF locations were geocoded and compared to patient addresses to determine proximity. Proximity was defined as < 4 miles to nearest site. Daily maximum particulate matter (PM2.5) measurements were sourced and merged with addresses; high exposure was defined as > 35 µg/m3. Multilevel regression analyses controlling for demographic and clinical factors were performed to assess associations between SF proximity, PM2.5 exposure, and likelihood of TNBC compared to other BCa subtypes. 3,181 patients with mean age 56  12 years were included. Eighty percent (n= 2,551) were White and 20% (n= 630) Black. Nineteen percent (n= 618) had TNBC. Forty-four percent (n= 1,410) lived close (< 4 miles) to SF. Two percent (n= 56) had "high" PM2.5 exposure. On multilevel analysis, patients living "close" to SF (OR 1.33, 95% CI 1.05-1.67, p= 0.015) and with "high" PM2.5 exposure (OR 2.09, 95% CI 1.04-4.02, p= 0.039) had higher TNBC likelihood. Living near SF and having "high" PM2.5 exposure were associated with higher TNBC likelihood. These findings merit further inquiry on the role of environmental contaminants on BCa subtype development. Residential exposure to SF and high PM2.5 levels may drive aggressive BCa biology, including TNBC.