Hair dye, chemical straightener use linked to onset of breast cancer

  • Eberle CE & al.
  • Int J Cancer
  • 3 Dec 2019

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

  • A prospective cohort of women whose sister had breast cancer finds increased risk of developing breast cancer associated with use of permanent hair dyes and chemical straighteners.
  • Black women using permanent hair dyes had up to 60% increased risk of developing breast cancer.

Why this matters

  • Use of permanent dyes is highly common, with 55% of cohort using them.
  • Hair products are known to contain endocrine-disrupting chemicals and carcinogens in animal studies.

Study design

  • Prospective cohort (n=46,709; aged 35-74 years) known as the Sister Study was of women free of breast cancer at enrollment but whose sister had breast cancer.
  • Funding: NIH.

Key results

  • Follow-up mean was 8.3 years.
  • Permanent hair dye (any use vs nonuse):
    • All women: HR, 1.09; 95% CI, 1.01-1.17.
    • White women: HR, 1.07; 95% CI, 0.99-1.16.
    • Black women: HR, 1.45; 95% CI, 1.10-1.90.
    • Black women with use every 5-8 weeks: HR, 1.60; 95% CI, 1.11-2.30.
  • Personal chemical straightener (any use vs nonuse):
    • All women: HR, 1.18; 95% CI, 0.99-1.41.
    • No differences by ethnicity.
    • Increased frequency of use carries higher risk (Ptrend=.02).

Limitations

  • Observational design.
  • Individual chemical constituents not studied.