Clinical Characteristics and Long-Term Outcomes of Young Women With Breast Cancer: A Multicenter Study From Uruguay

BACKGROUND: Breast cancer in women aged ≤40 years is uncommon but clinically challenging, often associated with aggressive pathological features and advanced-stage diagnosis. In Latin America, real-world data on long-term outcomes in this population remain limited. This study aimed to describe clinicopathological characteristics, treatment patterns, and survival outcomes of young women with breast cancer treated in Uruguay. METHODS: We conducted a multicenter retrospective cohort study including women aged 18-40 years diagnosed with invasive breast cancer between 2006 and 2024 at two public referral centers. Clinical, pathological, and treatment data were collected from medical records. Overall survival (OS) and disease-free survival (DFS) were estimated using Kaplan-Meier analysis. RESULTS: A total of 267 patients were included (mean age at diagnosis, 34.8 years). Invasive ductal carcinoma was the predominant histology (85.8%), with a high proportion of grade III tumors (39.3%). The most common biological subtype was luminal (48.8%), followed by HER2-positive (27.7%) and triple-negative disease (17.2%). Stage II disease was most frequent (40.4%), while 28.7% of patients presented with stage III disease. Modified radical mastectomy was the most commonly performed surgical procedure (38.2%). Most patients received surgery, radiotherapy, and systemic therapy according to recurrence risk. With a median follow-up of 52.3 months, estimated OS was 84.8% at 5 years and 80.9% at 10 years. Survival outcomes differed significantly according to clinical stage but not biological subtype. CONCLUSIONS: Young women with breast cancer in Uruguay frequently present with aggressive tumor features and advanced disease at diagnosis. Nevertheless, when managed within a multidisciplinary framework and treated according to current standards of care, long-term survival outcomes are favorable and comparable to international reports. These findings underscore the importance of early detection strategies and equitable access to guideline-based care in middle-income countries.