Cancer in Young Women: Late-stage Breast Cancer Registry Analysis of a 24-years Nationwide Retrospective Cohort of 52,734 Patients in Brazil

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Background Younger patients are not included in routine screening for breast cancer (BC) and can have delays in diagnostic evaluation. Particularly in Brazil, approximately 40% of women with breast cancer are diagnosed with late stage disease (III or IV), emphasizing persistent barriers to timely diagnosis and specialized care by the public healthcare coverage (The Brazilian Unified Health System; Sistema Único de Saúde; SUS). This study aims to estimate the frequency of late-stage BC (stages III or IV) at diagnosis among young women treated by (SUS) and identify associated sociodemographic and clinical factors. Material and methods Cross-sectional nationwide population-based study conducted to analyze data from the national Hospital Cancer Registry, including women aged 15 to 39 years diagnosed with BC, between 2000 and 2023. Results Nearly half (48.2%) of young women with breast cancer in Brazil are diagnosed at late stages (III–IV). In the multivariate analysis, self-reported Black or brown race (OR 1.18; 95%CI 1.12–1.25), education <9 years (OR 1.22; 95%CI 1.15–1.29), absence of a partner (OR 1.09; 95%CI 1.04–1.15), invasive carcinoma subtype of no special type (OR 1.16; 95%CI 1.08–1.25) and referral by the public system (OR 1.31; 95%CI 1.19–1.44) registered an independent association with late stage. Conclusion Brazil faces a high rate of late-stage breast cancer diagnoses among young women and the independent predictors of late presentation emphasizes the impact of social and structural inequities on oncology care. MicroAbstract Although breast cancer predominantly affects women older than 50 years, recent evidence has shown an increasing incidence among women younger than 40 years. Assessing nationwide data from the Brazilian Hospital Cancer Registries, this study analyzed 52,734 women aged 15–39 years and found that 48.2% were diagnosed with stage III–IV disease. Late presentation was independently associated with social vulnerability markers, including race, lower education, absence of a partner, and referral through the public health system. These findings highlight structural inequities in cancer care and provide evidence to inform policies aimed at improving early diagnosis in young women.