Study Reveals Significant Rise in Invasive Breast Cancer Among Asian American Women

A new study led by UC San Francisco has found a significant increase in the rates of invasive breast cancer among Asian American women over the past two decades, surpassing trends observed in any other ethnic group in the United States. This rise is particularly pronounced among women under 50 and those diagnosed with advanced stages of the disease or specific aggressive forms of breast cancer.

The findings, published in JAMA Network Open, indicate that breast cancer incidence has increased by over 3% per year for nearly all Asian American ethnic groups studied, with particularly sharp rises noted among Chinese and Vietnamese women. In contrast, Native Hawaiian women, who already represent one of the highest breast cancer rate groups in the U.S., have seen their rates climb by approximately 1% annually, a markedly slower rate compared to their Asian American counterparts.

Researchers suggest that increased breast cancer screening is unlikely to account for the upward trend, as such screenings typically facilitate earlier detection of cancers. However, the most significant increases have occurred in cases where the disease had already metastasized. Of particular concern is triple-negative breast cancer, the most aggressive subtype; among Chinese American women, instances of this condition rose more than 6% annually from 2017 to 2022.

“These patterns are highly concerning from a disparities standpoint,” stated Dr. Scarlett Lin Gomez, senior author and professor at UCSF’s Department of Epidemiology and Biostatistics. “They underscore why it is so important to move beyond treating Asian Americans, Native Hawaiians, and Pacific Islanders as a single population.”

A Closer Look at the Data

The research involved an analysis of around 150,000 invasive breast cancer cases diagnosed from 2000 to 2022, utilizing data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program. The study focused on nine distinct Asian American, Native Hawaiian, and Pacific Islander populations across 14 states, representing roughly two-thirds of the U.S. AANHPI population.

Traditionally, Asian American women, apart from Native Hawaiian women, have experienced lower breast cancer rates compared to non-Hispanic white women. However, this gap is rapidly closing; by 2022, incidence rates among Asian American women under 50 had become comparable to those of white women in the same age demographic.

The reasons behind the increase in breast cancer among younger women remain unclear. Researchers speculate that changes in reproductive patterns, dietary habits, and other lifestyle factors may influence the trend, but acknowledge that these elements alone do not explain the full scope of the findings. The team aims to explore additional causative factors through two UCSF-based initiatives, the CRANE breast cancer study and the ASPIRE cohort study.

“Understanding why breast cancer is increasing so rapidly in these communities is critical,” Dr. Gomez emphasized. “At the same time, we need to ensure that women across all Asian American, Native Hawaiian, and Pacific Islander communities have access to culturally appropriate education, screening, and timely follow-up care.”

Other contributors to the study include Meg McKinley, MPH; Katherine Lin, MPH; Iona Cheng, PhD; and Salma Shariff-Marco, PhD.

The research was supported by the Breast Cancer Research Foundation, as well as funding from the National Cancer Institute’s SEER Program and the Surveillance Research Program Division of Cancer Control and Population Sciences.