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Breast cancer rates have risen sharply among Asian American women over the past two decades, with increases occurring across nearly every ethnic group and at a faster pace than in any other US ethnic population, according to a new study led by researchers at the University of California, San Francisco (UCSF).
The study, published in JAMA Network Open, found that breast cancer incidence increased by more than 3% annually in nearly every Asian American ethnic group examined. The rise was even steeper among Chinese and Vietnamese American women.
The trend was particularly pronounced among women under 50 and among those diagnosed with advanced-stage or certain aggressive forms of breast cancer.
Native Hawaiian women already have among the highest breast cancer rates in the United States. However, their rates increased by about 1% annually, substantially slower than those recorded among most Asian American groups.
Researchers said increased breast cancer screening was unlikely to fully explain the trend. Screening generally leads to more cancers being detected at earlier stages, whereas the fastest increases in the study occurred among cancers that had already spread.
The researchers also identified a sharp rise in triple-negative breast cancer, one of the most aggressive breast cancer subtypes. Among Chinese American women, cases of the disease increased by more than 6% annually between 2017 and 2022.
“These patterns are highly concerning from a disparities standpoint,” said senior author Scarlett Lin Gomez, a professor of epidemiology and biostatistics at UCSF and co-leader of the Cancer Control Program at the UCSF Helen Diller Family Comprehensive Cancer Center.
The findings highlight the importance of examining Asian American, Native Hawaiian and Pacific Islander populations separately rather than treating them as a single group, she said.
Researchers analysed about 150,000 cases of invasive breast cancer diagnosed between 2000 and 2022. The data came from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program.
The analysis covered nine specific Asian American, Native Hawaiian and Pacific Islander (AANHPI) populations across 14 US states. Those states are home to about two-thirds of the country’s AANHPI population.
Historically, Asian American women, except Native Hawaiian women, have had lower breast cancer incidence rates than non-Hispanic white women.
That gap is now narrowing rapidly. By 2022, the breast cancer incidence rate among Asian American women under 50 had become comparable to that among white women in the same age group.
Researchers said the findings point to the need for more targeted research and prevention efforts that account for differences among individual Asian American and Pacific Islander populations.