Abstract Background: Breast cancer remains a major public health concern in Brazil, where advanced stage at diagnosis and delayed treatment initiation are key determinants of poor outcomes. In an effort to improve care, Brazil implemented the National Oncology Policy in 2005 and the “60-day Law” in 2012, mandating treatment initiation within two months of diagnosis. However, legal frameworks do not always translate into clinical reality. This study aimed to evaluate long-term temporal trends and regional disparities in breast cancer staging at diagnosis and treatment delays using national-level data from the Integrator of Brazilian Hospital Cancer Registries (IRHC). Methods: This was a cross-sectional, observational study utilizing secondary, anonymized data from the IRHC, which compiles standardized information from over 300 cancer hospitals across Brazil. Data spanning from 2000 to 2019 were included and categorized into three time periods: 2000-2005 (pre-National Oncology Policy), 2006-2012 (post-policy, pre-law) and 2013-2019 (post-law). Outcomes of interest were advanced stage at diagnosis (TNM stage ≥IIB) and treatment delay (defined as initiation 60 days from diagnosis). Statistical analyses included crude and adjusted odds ratios. A multiple logistic regression model incorporated confounders such as age, race, education level, and referral pathway. Analyses were performed using R software, version 4.4.2. All data were public and exempt from ethics review. Results: Among 282,419 breast cancer cases, the mean age was 55.1 years (SD 13.2), with 99.1% female patients and 30.6% identifying as non-white. The Southeast Region accounted for 56.3% of cases. Invasive ductal carcinoma was the most common histology (86.5%). More than half of the patients (55.0%) were diagnosed at an advanced clinical stage, and 54.4% underwent surgery as initial treatment. Adjusted analyses showed that patients diagnosed in the North (OR=1.60, p0.001), Northeast (OR=1.14, p0.001), and Midwest (OR=1.14, p0.001) were more likely to present with advanced disease compared to those in the Southeast, while the South showed a protective association (OR=0.84, p0.001). Advanced stage was also more common among non-white patients (OR=1.21, p0.001) and those without partners (OR=1.19, p0.001). Conversely, age over 50 (OR=0.68, p0.001), higher education (9 years; OR=0.70, p0.001), and referral from non-SUS services (OR=0.65, p0.001) were protective factors. Regarding time to treatment, delays were more frequent in the North (OR=1.23, p0.001), among non-white patients (OR=1.13, p0.001), and those aged 50 years (OR=1.26, p0.001). The Northeast (OR=0.78, p0.001) and South (OR=0.85, p0.001) showed lower odds of delay. Patients referred from non-SUS providers (OR=0.82, p0.001) or who were self-referred (OR=0.48, p0.001) also had shorter delays. Temporal analyses revealed that overall cancer staging trends remained stable or fluctuated without consistent decline, while treatment delays exceeding 60 days significantly increased. Conclusion: This 20-year nationwide analysis highlights persistent and substantial regional disparities in breast cancer staging and treatment delays in Brazil. Despite federal regulations such as the 60-day Law, treatment initiation beyond the legal window remains common, particularly in underserved regions. These findings underscore the need for improved implementation of oncology policies, especially in the North and Midwest, to ensure timely access to diagnosis and treatment. Strengthening referral pathways, increasing healthcare infrastructure, and addressing socioeconomic inequities are critical to narrowing Brazil’s regional cancer care gap. Citation Format: A. Dominique Nascimento Lima, L. Novis Leite Pinto, L. Martins de Brito Moraes, A. Mattar, E. Camargo Millen, F. Pimentel Cavalcante, F. Pereira Zerwes, M. Antonini, F. Palermo Brenelli, A. Frasson, A. Coelho de Oliveira, L. Mesentier da Costa, J. Bines. Regional disparities and temporal trends in breast cancer staging and time to treatment in Brazil: A 20-Year analysis of the hospital-based cancer registry abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS5-11-06.
Lima et al. (Tue,) studied this question.