Incidence trends in triple-negative breast cancer among women in the United States from 2010 to 2019 by race/ethnicity, age and tumor stage.

There were substantial ethnic disparities in the incidence rates of triple-negative breast cancer, but few studies were conducted on the incidence trend of triple-negative breast cancer by race/ethnicity. This study aimed to address the longer trends in the incidence of triple-negative breast cancer by race/ethnicity in women from 2010 to 2019, examine the incidence trends by patient age, tumor stage and time periods, and explore the changing proportions of three component receptors over time for triple-negative breast cancer. Our study identified 573,168 women with incident breast cancer at age ≥20 years between 2010 and 2019 in 18 SEER (Surveillance, Epidemiology, and End Results) registries. Of them, 62,623 (10.9%) were incident triple-negative breast cancer and 510,545 were non-triple negative breast cancer cases. The denominator of population included 320,117,009 women aged ≥20 in the same SEER areas. The study found that overall age-adjusted incidence rate of triple-negative breast cancer in women aged ≥20 years was 18.3 cases per 100,000 women. Age-adjusted incidence rate of triple-negative breast cancer was the highest in black women (33.8 cases per 100,000 women), followed by white (17.5), American Indian and Alaska Native (AIAN) (14.7), Hispanic (14.7), and Asian women (12.4). The significantly higher age-adjusted incidence of triple-negative breast cancer in black women as compared to white women appeared to be limited in younger women aged 20-44 only. Annual percentage changes in age-adjusted incidence of triple-negative breast cancer slightly decreased insignificantly in white, black and Asian women aged 20-44 and 45-54 years. There was a statistically significant annual percentage increase in age-adjusted incidence of triple-negative breast cancer in Asian and black women aged ≥55 years. In conclusion, there was a significantly higher incidence of triple-negative breast cancer in black women aged 20-44 years. From 2010 to 2019, there were no significant annual percentage changes in age-adjusted incidence of triple-negative breast cancer in all ethnic groups of women aged <55 years, with the exception of a significant decrease among AIAN women aged 45-54 years. However, there was a statistically significant annual percentage increase in age-adjusted incidence of triple-negative breast cancer in Asian and black women aged ≥55 years.