A new study by researchers at the American Cancer Society (ACS), published online May 22, 2024, in JAMA Network Open, found a significant increase in breast cancer incidence rates among women aged 20-49 in the United States between 2007 and 2019. The rates rose by an average of 3.8% annually, from 33.3 cases per 100,000 women in 2007 to 37.9 cases per 100,000 in 2019. Dr. Ahmedin Jemal, senior author and ACS senior vice president of surveillance and health equity science, stated, 'This is a concerning increase, particularly in young women for whom breast cancer is often more aggressive and diagnosed at later stages.'
The study revealed notable disparities, with Black and Hispanic women experiencing the largest increases in localized and regional breast cancer. Black women saw an average annual increase of 4.1% for localized and 6.0% for regional disease, while Hispanic women had increases of 3.2% and 5.2% respectively. The largest increases were observed in women aged 30-39 and 40-49, primarily for regional-stage disease. Additionally, rates of triple-negative breast cancer (TNBC), often more aggressive, increased, particularly among Black women, for whom it is most common.
The findings highlight the urgent need for updated screening guidelines, as current recommendations from organizations like the ACS typically advise starting mammograms at age 40 or 45, potentially missing these younger women. The authors emphasized the necessity for earlier detection strategies, especially for young Black and Hispanic women, who frequently face aggressive disease and later-stage diagnoses. They also called for more research to investigate potential causes for these increasing rates, including factors such as obesity, sedentary lifestyles, alcohol consumption, and exposure to endocrine-disrupting chemicals.
