Abstract PO3-09-11: Age Group Analysis of Breast Cancer Patterns in Brazil: Findings from Population-Based Registries
Authors: da Silva Jesse Lopes , De Melo Andreia Cristina , de Albuquerque Lucas Zanetti , Rodrigues Mariana Espirito Santo , Thuler Luiz Claudio Santos 
Published: May 2024

Abstract
Background: The rising breast cancer (BC) incidence among young women is potentially influenced by modifiable genetic and reproductive risk factors, as well as the increased incidence among older women may be associated with lifestyle-related factors and screening programs. This study examines BC incidence and mortality rates across different age groups in Brazil, focusing on clinicopathological and sociodemographic variations.
Patients and methods: By using data from 13 Brazilian Population-Based Cancer Registries spanning the period 2010-2015, this study analyzed incidence trends among women with BC. Crude incidence ratios (CIRs) and the annual average percent change (AAPC) were computed. Additionally, clinical and sociodemographic information from 348 Hospital-Based Cancer Registries covering 2000-2019 was incorporated. Mortality data for the years 2000-2020 were obtained from the National Mortality Information System. Comparative analyses were conducted across three predefined age groups: &lt; 40, 40-69, and ≥ 70 years. Statistical significance was defined as a p-value &lt; 0.05, while a threshold of more than 5% difference in proportional values was used as a criterion to identify clinically relevant differentials.
Results: Between 2010 and 2015, a total of 205,966 newly diagnosed cases of BC were documented. The CIRs were 7.1/100,000 for the age group &lt; 40, 156.5/100,000 for the age group 40-69, and 247.5/100,000 for the age group ≥ 70 years. Within the scope of the analyzed age groups, it was observed that solely the age group &lt; 40 years exhibited a noteworthy and persistent increase in the rate of occurrence (AAPC +1.6; 95% CI: 1.0 to 2.2; p &lt; 0.001). This age group also displayed a significantly higher proportion of black women (53%, p &lt; 0.001), a higher prevalence of alcohol consumption (20.5%, p &lt; 0.001), and a greater likelihood of receiving multiple treatment modalities (60.7%, p &lt; 0.001). In contrast, the age group ≥ 70 years experienced a more extended time delay of &gt; 60 days from diagnosis to treatment onset (54%, p &lt; 0.001), while exhibiting a higher utilization rate of hormone therapy (45.3%, p &lt; 0.01). The mortality rates witnessed a significant increase across all age categories, with the age group &lt; 40 years manifesting the most substantial escalation (AAPC +1.8%; 95% CI: 1.6 to 2.1; p &lt; 0.001). This rise was comparatively more than double the rate observed in the 40-69 age group (AAPC +0.7%; 95% CI: 0.5 to 0.8; p &lt; 0.001) and exactly twice as high as the rate recorded in the age group &gt; 70 years (AAPC +0.9%; 95% CI: 0.7 to 1.1 ; p &lt; 0.001).
Conclusion: This study reveals substantial disparities in BC incidence and mortality rates, as well as significant differences in clinicopathological and sociodemographic features, among women aged &lt; 40 compared to those in the 40-69 and ≥ 70 years in Brazil.
Keywords: Breast cancer; age groups; incidence; mortality.
Citation Format: Jesse Lopes da Silva, Andreia Cristina De Melo, Lucas Zanetti de Albuquerque, Mariana Espirito Santo Rodrigues, Luiz Claudio Santos Thuler. Age Group Analysis of Breast Cancer Patterns in Brazil: Findings from Population-Based Registries [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-09-11.