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Hair straighteners and the risk of uterine cancer: More studies are necessary to get this straight

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By Temitayo Ogunleye, MD, FAAD
Nov. 9, 2022
Vol. 4, No. 45

Headshot of Dr. Ogunleye
Every time the New York Times publishes a dermatology-related article I receive a flurry of text messages from friends and family and messages from patients. The most recent article discussing the possible link between the use of hair straighteners and uterine cancer was no different, perhaps even heightened given my clinical interests in hair loss/hair styling. (1) In the study reviewed, the researchers examined associations between hair product use and the incidence of uterine cancer among approximately 34,000 participants in the Sister Study, a United States/Puerto Rican cohort of breast cancer-free women aged 35-74 years who had a uterus at enrollment (2003-2009), who also had at least one sister diagnosed with breast cancer. (2) The Sister Study was established at the National Institutes of Health / National Institute of Environmental Health Sciences to investigate environmental and genetic risk factors for breast cancer but has since been used to identify possible links between environmental factors/exposures and other types of cancers.

Illustration for DWII on hair straighteners and the risk of uterine cancer
All women answered baseline questionnaires and self-reported their use of hair products in the prior 12 months, including hair dyes, straighteners, relaxers, pressing products, permanents, or body waves. The cohort was relatively racially/ethnically diverse, with Black (7.4%), Hispanic (4.4%), White (85.6%), and other race/ethnicity (2.5%) participants. They found that of women who had not used straighteners in the last year prior to baseline, approximately 1.64% were predicted to develop uterine cancer by age 70 years. The estimated risk was 1.18% higher for women who had ever used straighteners, and 2.41% higher for those with frequent use (greater than 4 times in the previous year). Other hair products such as dyes had no association. Compared with the overall cohort, “uterine cancer cases tended to be older with an earlier age at menarche, a higher BMI, and lower physical activity.” (2) Of note, most of the participants who had ever used straighteners were African American/Black (59.9%) and tended to be younger with a higher BMI and lower physical activity than those who didn’t use straighteners. (2)

What do we tell our patients about use of hair straighteners and its relation to uterine cancer?

The risk of uterine cancer is low, and even with the noted increases in risk, this relative increase in risk is still low. Furthermore, since the types of straighteners used were not specified, it is difficult to know what kinds of products patients should avoid. The questionnaire asked, “In the past 12 months, how frequently have you straightened or pressed your hair, or used hair pressing products,” which could include relaxers, keratin treatments, heat protectants, grease, or any other number of products. Also, while this study only proved association and not causality, since the women in the cohort specifically had a family history of breast cancer, it is possible that these women have a genetic susceptibility to ingredients in these products that may increase their risk but may not be generalizable.

That said, it is reasonable to recommend at least a reduction in frequency in use of various hair straightening products/methods to patients who are specifically concerned. Use 4 times per year or less reduced this association, and as dermatologists, we typically recommend limiting potentially damaging hair care behavior for improvement in hair loss/health anyway. Currently, there is not enough evidence to recommend discontinuation of straightening in all patients. Notably, the study confirmed known risk factors for uterine cancer such as age>50, obesity, and lower physical activity (related to obesity), so in patients who are concerned it is always helpful to reinforce other methods of reducing risk such as weight loss and exercise.

Point to Remember: A new study associated frequent use of hair straighteners with an increased risk of uterine cancer. This should be considered preliminary data. Until further studies are forthcoming, it would be prudent to advise our concerned patients who want to straighten their hair to diminish the frequency of use until this risk is defined further.

Our editor’s viewpoint

Warren R. Heymann, MD, FAAD

Along with Dr. Chris Adigun, I had the pleasure of being interviewed on the NPR broadcast “The People’s Pharmacy” on Saturday, Oct. 22, 2022 discussing topics related to hair and nails. Earlier that week, the New York Times article mentioned by Dr. Ogunleye was published. I was not aware of the article — I was much too ensconced in the Phillies’ magical run (congratulations Dusty Baker and the Houston Astros). When asked about it, all I could say was that I have not seen the original study, but, generally speaking, I would not panic or rely on a single epidemiological study — confirmatory studies are always warranted. Indeed, the conclusion of the abstract in Chang et al is: “These findings are the first epidemiologic evidence of association between use of straightening products and uterine cancer. More research is warranted to replicate our findings in other settings and to identify specific chemicals driving this observed association.” As Dr. Ogunleye correctly asserts — association does not mean causation. There are many variables in this study that must be sorted out before we tell our patients to avoid straightening their hair. Given the attention this article has received, I anticipate that further studies will define this association to help guide ourselves and our patients.

  1. Rabin, R. C. (2022, October 17). Hair straighteners may pose a small risk for uterine cancer, study finds. The New York Times. Retrieved October 28, 2022, from https://www.nytimes.com/2022/10/17/health/hair-straighteners-black-women-cancer.html

  2. Chang, C.-J., O’Brien, K. M., Keil, A. P., Gaston, S. A., Jackson, C. L., Sandler, D. P., & White, A. J. (2022). Use of straighteners and other hair products and incident uterine cancer. JNCI: Journal of the National Cancer Institute. https://doi.org/10.1093/jnci/djac165

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