Hair straightening chemicals may double the risk of uterine cancer, an official study suggests.
Research conducted by the National Institutes of Health (NIH) looked at 33,000 American women over more than a decade.
The uterine cancer rate was 4.05 percent among women who said they used chemical hair straighteners more than four times a year, compared with 1.64 percent among those who didn’t.
Scientists believe that chemicals in hair straightening creams seep into the bloodstream through the scalp and travel to the uterus.
Uterine cancer is uncommon, making up only about three percent of all cancer diagnoses in American women each year.
But researchers warn that numbers have risen in the US in recent years, especially among black women.
There are approximately 66,000 new cases of uterine cancer in the US each year, making it the most common cancer of the female reproductive system.
It is estimated that millions of American women use chemical hair straighteners every year.
Hair straightening chemicals could double uterine cancer risk, official study suggests (file image)
Warning signs include vaginal bleeding between periods, pelvic pain or cramping, and a white or clear vaginal discharge.
About 81 percent of patients are still alive for at least five years after their diagnosis, according to the American Society of Clinical Oncology.
But for black women, this rate drops to 63 percent, which experts say is due to the fact that they are more likely to have a more aggressive form.
Uterine Cancer: What Is It?
Uterine cancer is uncommon and accounts for three percent of all cases in women each year.
It describes two types of cancer: endometrium, in the lining of the uterus, or uterine sarcoma, in the muscle lining of the uterus.
Women are not normally screened for the cancer, but the endometrial type is usually diagnosed early to prevent its spread.
What are the symptoms?
- Bleeding from the vagina between periods;
- Vaginal bleeding after menopause;
- Pain or cramps in the pelvis;
- Thin, white or clear discharge.
How is it diagnosed?
Uterine cancer is diagnosed through a combination of blood tests and scans of the uterine area.
How is it treated?
Treatment options include chemotherapy and radiotherapy to destroy the cancer cells.
Surgery may also be offered in some cases of endometrial cancer.
What is the chance of survival?
The American Society of Clinical Oncology — experts in cancer research — say 81 percent of women diagnosed with cancer live longer than five years.
But for black women, the five-year survival rate is six percent.
They say this is because it is more aggressive in these individuals, although it is unclear why this is the case.
Source: Cleveland Clinic
In the first study of its kind, women between the ages of 35 and 74 were on studies for nearly 11 years.
There were 378 cases of uterine cancer at that time.
About 60 percent of women who used hair straightening creams were black, the scientists said, suggesting this group may be more at risk.
dr. Alexandra White, an epidemiologist at NIH who led the study, said, “The doubling rate is alarming. However, it is important to put this information into context – uterine cancer is a relatively rare cancer.
More research is needed to confirm these findings in different populations, to determine whether hair products contribute to health disparities in uterine cancer and to identify the specific chemicals that may increase the risk of cancer in women.
She added: “To our knowledge, this is the first epidemiological study to investigate the relationship between the use of hair straighteners and uterine cancer.”
All hair is made of a protein called keratin, which contains molecules called sulfides.
Sometimes these mate together to form a disulfide bond that creates curls in the hair.
Chemical straightening involves dissolving these disulfide bonds to change the structure of the hair.
This leads to curls that are ‘relaxed’ and straighten the hair.
The chemicals can be applied by a hairdresser at appointments costing up to $1,000 or at home.
They normally last several months, or until enough new hair has grown.
Use is more common among black women because they have much more curly hair.
In the paper, the scientists suggested that chemicals in the straighteners may enter the bloodstream through the scalp.
They would then, in turn, travel to the uterus, increasing the risk of cancer.
No brands or specific chemicals were examined in the study.
But scientists warned that parabens, bisphenol A, metals and formaldehyde — all used in chemical hair straighteners — may increase the risk of cancer.
Burns and lesions can exacerbate the rate at which it was absorbed, she added.
The research is published in the Journal of the National Cancer Institute.
It was based on 33,497 women who participated in the Sister Study, which examines factors that may increase the risk of certain cancers in women.
The participants were recruited from 2003 to 2009 and followed for approximately ten years.