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Exposures to carcinogens in hair products have been explored as breast cancer risk factors, yielding equivocal findings. We examined hair product use (hair dyes, chemical relaxers and cholesterol or placenta-containing conditioners) among African American (AA) and White women, and explored associations with breast cancer. Multivariable-adjusted models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) to describe the associations of interest among 2280 cases (1508 AA and 772 White) and 2005 controls (1290 AA and 715 White). Among controls, hair dye use was more common among Whites than AAs (58 versus 30%), while relaxer (88 versus 5%) and deep conditioner use (59 versus 6%) was more common among AAs. Among AAs, use of dark hair dye shades was associated with increased breast cancer risk (OR = 1.51, 95% CI: 1.20-1.90) and use of dark shades (OR = 1.72, 95% CI: 1.30-2.26) and higher frequency of use (OR = 1.36, 95% CI: 1.01-1.84) were associated with ER+ disease. Among Whites, relaxer use (OR = 1.74, 95% CI: 1.11-2.74) and dual use of relaxers and hair dyes (OR = 2.40, 95% CI: 1.35-4.27) was associated with breast cancer; use of dark hair dyes was associated with increased ER+ disease (OR = 1.54, 95% CI: 1.01-2.33), and relaxer use was associated with increased ER- disease (OR = 2.56, 95% CI: 1.06-6.16). These novel findings provide support a relationship between the use of some hair products and breast cancer. Further examinations of hair products as important exposures contributing to breast cancer carcinogenesis are necessary.

Introduction: Over the last several decades, the concern of environmental exposures to certain carcinogens and mutagens found in hair products, particularly hair dyes, have been explored for evidence of an association with breast cancer risk, yielding equivocal results. However, little is known about this association among African American (AA) women, who are common users of these products. The objective of this study was to examine the prevalence and patterns of use of hair products in AA and European American (EA) women in the Women's Circle of Health Study (WCHS), and their associations with breast cancer risk, overall and by estrogen receptor (ER+, ER-) and triple negative (TN) status. Methods: Data collection for the WCHS, a case-control study of breast cancer in New York City and several counties in New Jersey, was conducted through in-person interviews, with anthropometric and body composition measurements taken, and review of pathology records. At study entry, participants were asked on use of hair dyes, chemical relaxers/straighteners and cholesterol- and/or placenta-containing conditioning creams. Chi-square tests were used to compare differences in hair product variables by case-control status among AAs and EAs. Race-stratified, age-adjusted and multivariable-adjusted unconditional logistic regression models controlling for age, race, education, family history of breast cancer, oral contraceptive use, and body mass index were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between hair product use and risk among 4,285 women with breast cancer and controls (AA, n=2,798 and EA, n=1,487). Results: Among controls, 30.23% of AAs and 57.76% of EAs regularly used hair dye. Compared to light hair dye shades (blonde, light brown) use of darker shades (dark brown, black) was associated with increased odds of breast cancer among AA women (OR 1.64, 95% CI: 1.19-2.27), although there did not appear to be a dose response association with frequency of use. There were no associations between hair dye use and breast cancer risk among EA women. Use of chemical relaxers was more common among AAs than EAs (87.13% vs. 4.62% of AA and EA controls, respectively). Compared to AA women who used chemical relaxers without lye, those using products with lye were at increased risk (OR 1.54, 95% CI: 1.22-1.94). Among EA women although use of relaxers was not very common, compared to never users, those using relaxers (OR 1.74, 95% CI: 1.11-2.74) and using lye-containing relaxers (OR 4.37, 95% CI: 1.65-11.88) were at increased risk. Regular hair dye use (OR 1.20, 95% CI: 1.03-1.39), use of darker hair dye shades (OR 1.37, 95% CI: 1.05-1.77), and use of relaxers that contain lye (OR 1.26, 95% CI: 1.03-1.55) were associated with increased risk of ER+ BC. Regularly using both hair dyes and relaxers was associated with increased risk of ER+ BC (OR 1.20, 95% CI: 1.00-1.44). Regular hair dye use was not associated with risk of ER- or TNBC. The use of deep conditioning creams that contain cholesterol or placenta was also more common among AAs than EAs (56.12% vs. 6.01% of controls, respectively). However, there were no associations between use of these products and breast cancer risk. Conclusions: These findings from a large case-control study of AA and EA women provide additional epidemiological data to support a relationship between the use of some hair products, namely hair dyes and chemical relaxers, and risk of breast cancer. As use of various hair products and other cosmetics continue to increase among women in the U.S., particularly those at increased risk of breast cancer, improved awareness of the potential effects of exposures to their chemical ingredients are needed. Citation Format: Adana A.M. Llanos, Anna Rabkin, Gary Zirpoli, Cathleen Y. Xing, Bo Qin, Brian D. Gonzalez, Chi-Chen Hong, Kitaw Demissie, Elisa V. Bandera, Christine B. Ambrosone. Hair product use and breast cancer risk by hormone receptor status in the Women's Circle of Health Study. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr B81.