Breast Cancer Rates Are Rising Fastest Among Asian American Women, UCSF Study Finds

Breast cancer rates have been climbing faster among Asian American women than among any other ethnic group in the United States over the past two decades, according to a study led by the University of California, San Francisco (UCSF) and published in JAMA Network Open. Incidence rose by more than 3% a year in nearly every Asian American ethnic group examined, with even greater increases among Chinese and Vietnamese women.

The trend is most pronounced among women under 50 and in cancers diagnosed at an advanced stage or in aggressive subtypes. Among Chinese American women, cases of triple-negative breast cancer, considered the most aggressive subtype, increased by more than 6% a year between 2017 and 2022. Native Hawaiian women, who already have among the highest breast cancer rates in the country, saw a smaller annual increase of about 1%.

Researchers analyzed roughly 150,000 invasive breast cancer cases diagnosed from 2000 through 2022, using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) Program covering nine Asian American, Native Hawaiian and Pacific Islander populations across 14 states. Greater use of breast cancer screening probably does not explain the trend, the researchers said, since the fastest increases occurred in cancers that had already spread by the time they were diagnosed.

"These patterns are highly concerning from a disparities standpoint," said senior author Scarlett Lin Gomez, professor of epidemiology and biostatistics at UCSF. Asian American women, aside from Native Hawaiian women, have historically had lower breast cancer rates than non-Hispanic white women, but by 2022 incidence among Asian American women under 50 had become comparable to that of white women in the same age group. Researchers do not yet know what is driving the rise and say some risk factors affecting these communities may not yet have been identified.