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5MinuteConsult Journal Club

Chemical Hair Straightener and Risk for Uterine Cancer


J National Cancer Institute, djac165,

Study Summary

This is an observational study of sisters of women who developed a cancer or other chronic disease to determine if personal care products increased that risk in the sister without cancer. Almost 34,000 women (35-74) were included; with 85% white and 7% black; 4% Hispanic.

Over 10 years of follow up, those who used chemical hair straighteners had an increased risk of developing uterine cancer (HR = 2.55; 95% CI 1.46-4.45). Greatest risk was associated with use >4 times in previous 12 months. Over a lifetime, this estimates a risk of uterine cancer of 1.64% for those who never use a hair straightener vs 4.05% in those who use them frequently


In women whose sisters have a cancer or other chronic disease, using a chemical hair straightener may increase your risk of developing uterine cancer.


This is a very curious approach to this study: a relationship of an optional exposure (hair product) to a disease. By using sibling data on cancers and other chronic conditions, they identified a risk factor for the unaffected sibling for uterine cancer.

While this study population contained a majority of white women, almost 60% of black women in the study use a chemical hair straightener.

The takeaway here is their risks are likely even larger than this study can estimate. Thus, encourage all women, but especially those with siblings with hormone related disease and cancer, to limit/NOT use a chemical hair straightener.

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