Incidence trends of advanced breast cancer in an era of its routine screening in the United States: A population-based study.

10523 Background: One of the purposes of routine screening for cancers is to delay the time of diagnosis of the late or advanced stages of the disease. Breast cancer screening is recommended for women aged 40 years and above. Over 70% of women reported receiving mammograms in the last two years between 2001 and 2020. Despite widespread screening, the impact on incidence trends of advanced breast cancer (aBC) in real-world settings in the last two decades is largely unknown. Methods: This population-based study identified adults aged 40–74 with regional/distant stage breast cancer (advanced) diagnosed between 2004 and 2020, using the Surveillance, Epidemiology, and End Results, 17 Research Plus registries. Age-adjusted incidence rates (AAIR) per 100,000 persons were extracted for aBC, with rates age-adjusted to the US standard population. The annual percentage change (APC) of the age-standardized incidence rate was estimated with the Joinpoint regression program. The APC was used to compare incidence trends stratified by age (40-54 vs. 55-74 years), race/ethnicity, and area of residence. Results: A total of 194,946 cases of aBC were diagnosed between 2004 and 2020; 120 257 (61.7%) were Non-Hispanic White (NHW), 28 585 (14.7%) were Hispanics, 25 691 (13.2%) were Non-Hispanic Black (NHB), 18 192 (9.3%) were Non-Hispanic Asian or Pacific Islander (NHAPI), 1326 (0.7%) were Non-Hispanic American Indians/Alaska Natives (NHAIA), and 895 (0.5%) were of unknown race/ethnicity. From 2004 to 2020, the overall AAIR of aBC showed an increase (APC, 0.2%: 0.00 – 0.40), with a notable rise in NHAPI (APC, 1.43%: 1.00 – 1.90) and Hispanics (APC of 0.66% (0.24 – 1.15), while remaining stable in other racial groups. Additionally, the AAIR increased among individuals aged 40-54 years (APC, 0.58%: 0.38 – 0.79) but was stable in those between 55-74 years. Regarding the area of residence, there was a significant increase in non-metropolitan areas (APC, 0.65%: 0.38 – 0.93), contrasting with no significant change in metropolitan areas. Conclusions: Despite widespread breast cancer screening, the occurrence of aBC has persistently increased, especially among individuals aged 40 to 54 years, NHAIA, and in non-metropolitan areas. Further studies are needed to establish the underlying reasons for these observed trends.