Dibutyl phthalate: high exposure tied to breast cancer in Danish study

  • Ahern TP & al.
  • J Clin Oncol
  • 17 Apr 2019

  • curated by Miriam Davis, PhD
  • Univadis Clinical Summaries
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Takeaway

  • High cumulative exposure to dibutyl phthalate (DBP) is associated with increased breast cancer risk, according to a Danish nationwide population-based study.

Why this matters

Study design

  • Population-based cohort of 1.12 million breast-cancer-free women on January 1, 2005, using a Danish Medicines Agency ingredient database, the National Prescription Registry, and the Danish Cancer Registry.
  • Phthalate exposure based on prescription claims.
  • Funding: Susan G. Komen for the Cure; NIH.

Key results

  • More than 9.99 million women-years of follow-up (median, 10 years); 27,111 cases of invasive breast cancer occurred (estrogen receptor [ER] positive, 84%).
  • Approximately 14% of the cohort (n=161,737) used phthalate-containing medications.
  • Near-null associations were found for invasive breast cancer and diethyl phthalate, cellulose acetate phthalate, hypromellose phthalate, and polyvinyl acetate phthalate.
    • Associations remained near-null in ER-specific models.
  • The highest level of cumulative DBP exposure (≥10,000 cumulative mg) was associated with nearly doubled risk for incident breast cancer (aHR, 2.0; 95% CI, 1.1-3.6), driven entirely by an association with ER+ breast cancer (aHR, 1.9; 95% CI, 1.1-3.5).
    • ER breast cancer: aHR, 0.99; 95% CI, 0.14-7.0.

Limitations

  • Study could not adjust for adiposity.
  • Observational design.