Abstract P5-04-10: Age at Breast Cancer Diagnosis and Associated Demographic Factors: An Epidemiological Study in Brazil

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Abstract Background: In recent years, shifts in the median age at breast cancer (BC) diagnosis have been observed in various countries. Multiple factors influence these changes, including demographic shifts, sex, lifestyle modifications, and genetic factors. As populations age and demographics change, there may be significant impacts on these trends. Lifestyle factors such as diet, exercise, and environmental factors also play a role. Genetic research has emphasized the role of inherited factors in BC age onset. This study aims to analyze the trends in median age at BC diagnosis in Brazil, focusing on sociodemographic aspects like the distribution of the Human Development Index (HDI), sex, and variations among different racial and ethnic groups based on race/skin color. Patients and methods: Data from 32 Brazilian Population-Based Cancer Registries spanning 1990 to 2020 were used to analyze BC median age trends based on age at diagnosis, sex, racial group, and geographical region. Racial and skin color information was collected through self-declaration aligning with categories like white, indigenous, yellow (Asian), black, and mixed race set by the Brazilian Institute of Geography and Statistics. Due to limited HDI data for Brazilian states and municipalities in 2000 and 2010, a mean HDI estimated for 2005 was utilized. Variations in the mean HDI for the year 2005 were observed across municipalities, with classifications ranging from low HDI (0.50 to 0.59) to moderate HDI (0.60 to 0.69), high HDI (0.70 to 0.79), and very high HDI (0.80 to 1.00). Analysis of median age trends employed Joinpoint models, with the Joinpoint Regression Program providing confidence intervals to assess the null hypothesis of APC = 0 and p-values to evaluate potential trend changes. Statistical significance was determined at p < 0.05. Results: Between 1990 and 2020, there were 227,896 new documented cases of breast cancer (BC). After excluding 7,850 cases with missing sex or age data, 225,436 cases were analyzed. Among these cases, 99.2% were female and 0.8% were male, resulting in a ratio of 1 man for every 120 women diagnosed. The median age at diagnosis in Brazil was 56 years. Municipalities with lower and moderate HDI levels had a lower median age at diagnosis of around 53 years. Conversely, regions with higher and very high HDI levels showed a higher median age at diagnosis, ranging between 56 and 58 years, respectively. Black and Indigenous patients had a younger median age at diagnosis (54 years) compared to white patients (58 years). The median age at diagnosis of breast cancer has shown an increase over the last decade, attributed to improvements in HDI, with the most significant rise observed in the northern region of Brazil. Conclusion: This study highlights significant differences in the median age at breast cancer diagnosis across different regions, with earlier onset associated with lower HDI areas. Furthermore, Black and Indigenous patients exhibited a younger median age of diagnosis, reflecting previous research that has shown disparities in BC within the Brazilian population concerning race. Citation Format: Jesse Lopes da Silva, Natalia Cristina Cardoso Nunes, Lucas Zanetti de Albuquerque, Pedro Henrique Souza, Andréia Cristina de Melo, Luiz Claudio Santos Thuler. Age at Breast Cancer Diagnosis and Associated Demographic Factors: An Epidemiological Study in Brazil [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P5-04-10.

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