Chemical hair relaxer use and its potential effect on incidence of endometrial cancer in Black women.

e17591 Background: Research is being conducted to determine chemical hair relaxer’s effects on women’s risk of endometrial cancer (EC). Recent studies have suggested that frequent use (>4 times/year) of chemical relaxers increases incidence of EC by a hazard ratio of 2.55. Black women purchase 60% of chemical straighteners in the United States while being 6.5% of the population. Hair relaxer can be made from sodium hydroxide, lithium hydroxide, or potassium hydroxide. These chemicals can cause a hormone imbalance with estrogen, leading to increased endometrial cancer incidence. This study aims to correlate population data of endometrial cancer and hair relaxer to explain the increased incidence of gynecologic cancer in Black women. Methods: The average rate of incidence per 100,00 per year for endometrial cancer for White and Black women were obtained from the National Program of Cancer Registries and Surveillance, Epidemiology, and End Results Program SEER*Stat Database: NPCR and SEER Incidence – U.S. Cancer Statistics 2001–2019 Public Use Research Database. Chemical relaxer was first commercially available in 1971. The average age of endometrial cancer diagnosis was obtained from the National Cancer Institute. Results: Nineteen years of data was collected from the SEER database. EC had 222,464 cases total. In the year 2001, EC incidence was most common in White women at a rate of 25 per 100,000. Black women were second, at a rate of 20 per 100,000. In 2017, Black women surpassed White women for most incidence with a rate of 28, in comparison to White women's rate of 27.5 per 100,000. In the year 2019, Black women increased to the rate of 29 per 100,000, which was greater than White women's rate at 27.6 per 100,000. Conclusions: Studies have shown that ever use of hair relaxer in the past 12 months is associated with higher incidence of EC. The hazard ratio increases to 2.55 when hair relaxer is used 4 or more times per year. The National Cancer Institute states that the average age to be diagnosed with EC is 60 years old for all races of women. Because hair relaxer was made commercially available in 1971, the year 2017 would be when women at the average age of diagnosis would have access to hair relaxer their entire lives. 2017 is also the year when Black women became the racial group with the highest incidence of EC in the United States. Hair relaxer could be an important variable as to why EC incidence in Black women has surpassed White women. In the future, this information could be used to risk stratify women for cancer surveillance or have warning labels placed on hair relaxer boxes.