Abstract
BACKGROUND: 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 of Superfund (SF) site and poor air quality exposure with TNBC. METHODS: A retrospective review was performed for patients with stage I to IV breast cancer treated between 2005 and 2018. SF locations were geocoded and compared with patient addresses to determine proximity. Proximity was defined as <4 miles to the 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 among SF proximity, PM2.5 exposure, and likelihood of TNBC compared with other breast cancer subtypes. RESULTS: A total of 3,181 patients with a mean age 56 ± 12 years were included. Eighty percent (n = 2,551) were White, and 20% (n = 630) were Black. Nineteen percent (n = 618) had TNBC. Forty-four percent (n = 1,410) lived close (<4 miles) to SF sites. Two percent (n = 56) had "high" PM2.5 exposure. On multilevel analysis, patients living "close" to SF (OR = 1.33; 95% confidence interval, 1.05-1.67; P = 0.015) and with "high" PM2.5 exposure (OR = 2.09; 95% confidence interval, 1.04-4.02; P = 0.039) had higher TNBC likelihood. CONCLUSIONS: Living near SF sites and having "high" PM2.5 exposure were associated with higher TNBC likelihood. These findings merit further inquiry on the role of environmental contaminants on breast cancer subtype development. IMPACT: Residential exposure to SF sites and high PM2.5 levels may drive aggressive breast cancer biology, including TNBC. See related In the Spotlight, p. 7.