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Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women
Author(s) -
Eberle Carolyn E.,
Sandler Dale P.,
Taylor Kyla W.,
White Alexandra J.
Publication year - 2019
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.32738
Subject(s) - breast cancer , medicine , hazard ratio , proportional hazards model , prospective cohort study , population , cohort study , cancer , confidence interval , gynecology , oncology , obstetrics , environmental health
Many hair products contain endocrine‐disrupting compounds and carcinogens potentially relevant to breast cancer. Products used predominately by black women may contain more hormonally‐active compounds. In a national prospective cohort study, we examined the association between hair dye and chemical relaxer/straightener use and breast cancer risk by ethnicity. Sister Study participants ( n = 46,709), women ages 35–74, were enrolled between 2003 and 2009, and had a sister with breast cancer but were breast cancer‐free themselves. Enrollment questionnaires included past 12‐month hair product use. Cox proportional hazards models estimated adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between hair products and breast cancer; effect measure modification by ethnicity was evaluated. During follow‐up (mean = 8.3 years), 2,794 breast cancers were identified. Fifty‐five percent of participants reported using permanent dye at enrollment. Permanent dye use was associated with 45% higher breast cancer risk in black women (HR = 1.45, 95% CI: 1.10–1.90), and 7% higher risk in white women (HR = 1.07, 95% CI: 0.99–1.16; heterogeneity p = 0.04). Among all participants, personal straightener use was associated with breast cancer risk (HR = 1.18, 95% CI 0.99–1.41); with higher risk associated with increased frequency ( p for trend = 0.02). Nonprofessional application of semipermanent dye (HR = 1.28, 95% CI 1.05–1.56) and straighteners (HR = 1.27, 95% CI 0.99–1.62) to others was associated with breast cancer risk. We observed a higher breast cancer risk associated with any straightener use and personal use of permanent dye, especially among black women. These results suggest that chemicals in hair products may play a role in breast carcinogenesis.