Abstract PS5-12-01: Breast cancer in chile: incidence rising, young women dying, why?

Abstract Introduction In Chile, official databases on mortality and hospitalizations systematically record all events, identifying causes using the ICD-10 coding system. Since 2005, the Explicit Health Guarantees (GES) program has provided time-bound treatment and financial coverage for specific conditions, including breast cancer (BC). In 2024, we conducted a descriptive-analytical study using official secondary databases from Chile, covering mortality from 1997 to 2023. We found that the BC mortality rate increased by 19.2% among women under the age of 40, while it decreased by 21% among women aged 40 and older. Objective: To describe the incidence of BC in Chile, with a specific focus on women under 40 years of age. Materials and methods: This is a descriptive study. For incidence, data from the GES program were used as a proxy. We analyzed the period between 2007 and 2023. All data sources had near-complete national coverage. The study variables included: Temporal trends (year of event) through Annual Percentage Change (APC), individual characteristics (age), and disease coding using ICD-10 code “C50” for BC. Due to the case distribution, incidence trends were examined annually. Crude and age-adjusted rates were calculated. Temporal trends were assessed using Joinpoint regression models (Version 5.2). Data were processed using R software (2023). Results According to GES data, from 2007 to 2023: • The number of new BC cases in women under 40 increased with an APC of 7.42% between 2014 and 2023. • Among women aged ≥40, incidence rise of BC by an APC of 9.94% between 2020 and 2023. • The crude incidence rate of BC per 100,000 women aged 20-39 increased from 8.7 in 2007 to 19.75 in 2023 (+227%), indicating a concerning upward trend among younger women. • For women ≥40, the crude incidence rate of BC rose from 104.82 in 2007 to 162.00 in 2023 (+154%). • Among women under 40 years old, the APC was 4.82, indicating a faster rise in incidence rates between 2007 and 2023. In contrast, women over 40 years old experienced a more gradual increase, with an APC of 2.15 Conclusions At SABCS 2024, we reported a 19.2% increase in BC mortality among women under 40, with this trend accelerating after 2015, while mortality decreased by 21% in women over 40. In this report, we present incidence data from 2007 to 2023, revealing a faster rise among younger women. It is important to note that the increase in mortality among women