New research finds link between hair straightening products and cancer, know details

Uterine cancer is one of the most common gynaecologic cancers. Uterine cancer, also called endometrial cancer, is the sixth most commonly occurring cancer for women around the world, with more than 417,000 cases reported in 2020. Research shows the rate of endometrial cancer increased globally from 1990 to 2019.

Overall, incidence and mortality rates have increased in the United States in the past 2 decades, with more than 65,950 new cases and 12,550 deaths expected in 2022. Exposure to excess estrogen and a hormonal imbalance of estrogen and progesterone have been identified as key risk factors for uterine cancer. Hence, it has been hypothesized that synthetic estrogenic compounds such as endocrine-disrupting chemicals (EDCs) could contribute to uterine cancer risk because of their ability to alter hormonal actions.

What is uterine cancer?

Uterine cancer occurs in the uterus which is a female organ involved in reproduction. The uterus is also called a womb.

The most common type of uterine cancer, known as endometrial cancer, happens in the inner lining of the uterus, called the endometrium. Uterine cancer can also take place in the muscle wall of the uterus called the myometrium.

Risk factors for uterine cancer include:

• Age
• Obesity
• Family history
• Type 2 diabetes
• Exposure to or imbalance of estrogen.

Symptoms of uterine cancer include:

• Unusual bleeding between menstrual cycles or after menopause
• Pelvic pain
• Pain during urination
• Fatigue
• Nausea
• Feeling of heaviness in the pelvic area
• Weight loss.

Research connecting uterine cancer with hair straightening chemicals

According to a new large study from the National Institutes of Health (NIH), women who use chemical hair-straightening products may be at higher risk for uterine cancer than women who don’t. Study participants who reported frequent use of hair-straightening products, defined as more than four times in the previous year, were more than twice as likely to go on to develop uterine cancer as those who did not use the products. The findings were published on October 17 in the Journal of the National Cancer Institute.

Alexandra White, PhD, the head of the NIEHS Environment and Cancer Epidemiology group in Research Triangle Park, North Carolina mentioned the details about the disturbing increase in uterine cancer in a press release. She said the doubling rate is concerning as uterine cancer is a relatively rare type of cancer to begin with.

Uterine cancer occurs when malignant (cancer) cells form in the tissues of the endometrium, which is the lining of the uterus. It accounts for about 3 per cent of all new cancer cases, according to the National Cancer Institute, but it’s the most common cancer of the female reproductive system, with 65,950 estimated new cases in 2022.

Unlike those of many cancers, the incidence and death rates for uterine cancer are rising. New cases have risen by 0.6 per cent per year from 2010 to 2019, and death rates have risen an average of 1.7 per cent per year during the same time frame.

Hair products such as dye and chemical straighteners contain a number of different chemicals that may act as carcinogens or endocrine disruptors, and thus may be important for cancer risk.

“Straighteners in particular have been found to include chemicals such as phthalates, parabens, cyclosiloxanes, [and] metals, and can release formaldehyde when heated,” Dr. White told Medical News Today.

While previous research has suggested that hair dye and chemical straighteners are related to other hormone-sensitive cancers, such as breast and ovarian cancer, no previous study has considered how they are related to the risk of uterine cancer.

For this study, Dr. White and her team studied data from over 33,000 women in the United States aged 35–74 years participating in the Sister Study. The NIEHS conducts the Sister Study in an effort to identify breast cancer risk factors and other health issues.

Researchers followed women participating in the study for about 11 years. During that time, 378 cases of uterine cancer were diagnosed.

Upon analysis, the scientists found that women who said they used hair straightening products more than four times in 1 year were more than twice as likely to develop uterine cancer than those who did not use the products.

“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%,” Dr. White said.

Researchers also reported not finding any increased risk for uterine cancer for women using other hair care products such as hair dyes, highlighting products, bleach, or perming products.

Increased risk for black women

According to researchers, 60% of participants who used hair straightening products self-identified as Black women. Although scientists did not find a link between chemical hair straightener use, uterine cancer diagnosis, and race, the research team reported Black women may be at increased risk due to higher use of chemical hair straighteners.

“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,” states Dr. Che-Jung Chang, a research fellow in the NIEHS Epidemiology Branch and member of the study’s research team.

A study from June 2022 found that incidents of uterine cancer were on the rise among non-Hispanic Black women. This same study also found that Black women had more than double the mortality rate compared to other racial and ethnic groups.

It should be noted that a few days after this study was published, a US woman sued the French cosmetic giant, L’Oreal, for giving her uterine cancer. As per the reports, Jenny Mitchell, who has been using L’Oreal’s chemical hair straightening products for more than two decades, filed a civil lawsuit against the brand claiming it has caused her uterine cancer and forced her to undergo a full hysterectomy.