Scientists have linked frequent use of hair-straightening and other hair products to uterine cancer.
“We estimated that 1.64% of women who never used hair straighteners would go on to develop uterine cancer by the age of 70, but for frequent users, that risk goes up to 4.05%,” said study leader Alexandra White of the US National Institute of Environmental Health Safety (NIEHS).
Researchers tracked 33 947 racially diverse women, aged 35 to 74, for an average of nearly 11 years. During that time, 378 of them developed uterine cancer, reports The Guardian.
After researchers accounted for participants’ other risk factors, the odds of developing uterine cancer were more than two and a half times higher for women who had used straightening products more than four times in the previous year.
Less frequent straightener use in the past year also was associated with an elevated uterine cancer risk, but the difference was not statistically significant, meaning it might have been due to chance.
Earlier studies have shown that hair straighteners contain so-called endocrine-disrupting chemicals. The products have previously been associated with higher risks of breast and ovarian cancer.
“These findings are the first epidemiologic evidence of association between use of straightening products and uterine cancer,” White and colleagues wrote in the Journal of the National Cancer Institute. “More research is warranted to … identify specific chemicals driving this observed association.”
The link between straightener use and uterine cancer did not differ by race in the study.
But “because black women use hair straightening or relaxer products more frequently and tend to initiate use at earlier ages than other races and ethnicities, these findings may be even more relevant for them”, said Che-Jung Chang of NIEHS.
Study details
Use of Straighteners and Other Hair Products and Incident Uterine Cancer
Che-Jung Chang, Katie O’Brien, Alexander Keil, Symielle Gaston, Chandra Jackson, Dale Sandler, Alexandra White.
Published in the Journal of the National Cancer Institute on 17 October 2022
Abstract
Background
Hair products may contain hazardous chemicals with endocrine-disrupting and carcinogenic properties. Previous studies have found hair product use to be associated with a higher risk of hormone-sensitive cancers including breast and ovarian cancer; however, to our knowledge, no previous study has investigated the relationship with uterine cancer.
Methods
We examined associations between hair product use and incident uterine cancer among 33 947 Sister Study participants aged 35-74 years who had a uterus at enrolment (2003-2009). In baseline questionnaires, participants in this large, racially and ethnically diverse prospective cohort self-reported their use of hair products in the prior 12 months, including hair dyes; straighteners, relaxers, or pressing products; and permanents or body waves. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) to quantify associations between hair product use and uterine cancer using Cox proportional hazard models. All statistical tests were 2-sided.
Results
Over an average of 10.9 years of follow-up, 378 uterine cancer cases were identified. Ever vs never use of straightening products in the previous 12 months was associated with higher incident uterine cancer rates (HR = 1.80, 95% CI = 1.12 to 2.88). The association was stronger when comparing frequent use (>4 times in the past 12 months) vs never use (HR = 2.55, 95% CI = 1.46 to 4.45; Ptrend = .002). Use of other hair products, including dyes and permanents or body waves, was not associated with incident uterine cancer.
Conclusion
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.
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