TOPLINE

Chinese, Filipina, and Japanese women with breast cancer had lower all-cause mortality than non-Latina White women, even after adjusting for clinical, sociodemographic, and lifestyle factors, in a pooled cohort study. These Asian subgroups were less likely to die despite having more unfavorable tumor characteristics.

METHODOLOGY

• Breast cancer mortality rates after diagnosis are lower in Asian women than in non-Latina White women, although reasons for this difference are not well understood.
• Researchers pooled data from four epidemiologic studies conducted in California and Hawaii, analyzing 8994 women (mean age at diagnosis, 59 years) with first primary invasive breast cancer diagnosed from 1992 to 2019, including 3973 Asian and 5021 non-Latina White women.
• Participants self-identified as Chinese, Filipina, Japanese, Korean, South Asian, Vietnamese, another Asian ethnic group, Asian and Native Hawaiian or Pacific Islander, Asian and multiple races or ethnicities, or non-Latina White, with information collected from questionnaires and cancer registries.
• Hazard ratios (HRs) were estimated to compare each Asian group with White women, adjusting for clinical factors (stage, tumor grade, and treatment), sociodemographic factors (marital status, education, and insurance), reproductive factors, lifestyle factors (smoking, alcohol, and BMI), diabetes, and neighborhood socioeconomic indicators.
• Outcomes of interest were all-cause and breast cancer-specific mortality, with a mean follow-up time of 12.6 years (range, 1 month to 28 years), during which 2637 total deaths and 1140 breast cancer-specific deaths occurred.
• Analysis was conducted from February 2024 to February 2026, with race and ethnicity evaluated as social constructs and nativity (born outside the US vs US born) examined in combination with racial and ethnic groups.

TAKEAWAY

• In fully adjusted models, Chinese women had lower all-cause mortality (HR, 0.77), as did Filipina women (HR, 0.81), Japanese women (HR, 0.71), and Asian women identifying as multiple races or ethnicities (HR, 0.67) than White women.
• Lower adjusted likelihood of all-cause mortality was observed for Chinese (HR, 0.73) and Filipina (HR, 0.79) women born outside the US and Japanese women (HR, 0.63) and Asian women with multiple races or ethnicities (HR, 0.59) born in the US vs White women.
• Most Asian groups had higher proportions diagnosed before age 50 (34% among Filipinas to 73% among another Asian group) compared with White women (15%), and nearly all Asian ethnic groups had lower proportions of localized stage disease (45%-67%) than White women (69%).
• Breast cancer-specific mortality among Asian women was similar to that among White women, with HR estimates < 1.0 but not statistically significant for all Asian groups except for the Asian and Native Hawaiian or Pacific Islander group.

IN PRACTICE

“In this pooled cohort study of females with breast cancer, several Asian groups had lower risk of all-cause mortality, even after accounting for clinical, sociodemographic, reproductive, lifestyle, and neighborhood factors. Identification of the specific resiliency factors will provide insights into mechanisms that may improve survival after breast cancer,” authors of the study wrote.

SOURCE

The study was led by Scarlett Lin Gomez, PhD, University of California, San Francisco. It was published online on July 1 in JAMA Network Open.

LIMITATIONS

According to the authors, potential limitations included heterogeneity across the four pooled studies, including differences in inclusion criteria, selection and response biases, variability in survey instruments, and timing of study enrollment (three post-diagnosis and one pre-diagnosis). The study lacked detailed treatment information and had incomplete data on ERBB2 status, which was available for only 20% of Asian and 40% of White participants. The study did not include detailed information on length of residence in the US for women born outside the US. The study included diagnoses from 1992 through 2019, a wide time range in which secular trends in breast cancer diagnosis and treatment may have affected results.

DISCLOSURES

This research received support from grant ROICA241125 from the National Cancer Institute, with Gomez as the contact multiple principal investigator. The contributing studies received funding as follows: the Asian American Breast Cancer Study received support from the California Breast Cancer Research Program (grants 1RB-0287, 3PB-0120, 5PB-0018, and 1OPB-0038); the Multiethnic Cohort received support from the National Cancer Institute (grant UO1 CA164973); the Northern California Breast Cancer Family Registry received support from the National Cancer Institute (grant UO1CA164920); and the Pathways Study received support from the National Cancer Institute (grant U01CA195565). The collection of cancer incidence data used in this study received support from the California Department of Public Health, CDC’s National Program of Cancer Registries, and the National Cancer Institute’s Surveillance, Epidemiology and End Results Program. Brittany N. Morey, PhD, disclosed receiving grants from National Cancer Institute; National Institute on Minority Health and Health Disparities; American Cancer Society; Pfizer; and University of California, San Francisco, California Collaborative for Public Health Research outside the submitted work. No other disclosures were reported.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.