Is Contaminated Drinking Water Tied to HR+ Breast Cancer?

TOPLINE:
Women exposed to drinking water contaminated with high levels of synthetic chemicals known as perfluoroalkyl substances (PFAS) are not at an elevated risk for hormone receptor-positive (HR+) breast cancer, a prospective cohort study from Sweden finds.
METHODOLOGY:
This study was a prospective cohort of all women residing in the southern Swedish municipality of Ronneby from 1985 to 2013 (n = 24,509).
In 2013, one of two Ronneby waterworks was found to have contaminated drinking water with high levels of PFAS dominated by perfluorooctane sulfonic acid and perfluorohexane sulfonic acid.
Women in the cohort with a breast cancer diagnosis, during 2006-2016 (n = 313), had individual exposure assessment performed based on municipality waterworks distribution data linked to their annual residential address.
In all, 224 cases of breast cancer received adjuvant endocrine therapy according to the Prescribed Drug Register. Being prescribed adjuvant endocrine therapy was a proxy measure for HR+ breast cancer.
Women ever vs never living at a residential address with high PFAS exposure were compared for risk for HR+ breast cancer.
TAKEAWAY:
Women ever living at a residential address with high PFAS in drinking water were not at an elevated risk for HR+ breast cancer compared with women never living at an address with high PFAS in drinking water (hazard ratio, 0.84; 95% CI, 0.61-1.14).
Subgroup analysis found no relationship between prepubertal exposure and HR+ breast cancer and no relationship between exposure and having a HR+ breast cancer diagnosis before or after age 50 years.
IN PRACTICE:
In this first longitudinal study of its kind, the authors concluded, “Our findings do not indicate an increased risk of hormone receptor-positive breast cancer following high PFAS exposure … [yet] further epidemiological studies with focus on early-life exposure are warranted.”
SOURCE:
The lead and corresponding author is Sofia Hammarstrand of the University of Gothenburg, Gothenburg, Sweden. The study appeared in Environment International.
LIMITATIONS:
Limitations included the study’s observational design.
DISCLOSURES:
None of the authors declared competing interests. Funding was from the Swedish Research Council and the Swedish federal government.
 
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