Background: Breast cancer (BC) in women under 45 years represents a distinct clinical entity, frequently associated with aggressive biological features.However, integrated clinico-pathological and genomic data in this population remain limited.We aimed to characterize the clinical, pathological and molecular features of young women breast cancer (YWBC).Methods: This prospective single-center study included women aged 18-45 years diagnosed with BC from January 2023 to December 2024.Clinical data, germline testing, immunohistochemistry (IHC), and molecular assays (Prosigna/PAM50, HER2DX or TNBCDX) were collected.Descriptive analyses were performed.Results: Forty-five patients were included (median age 37.5 years).Key clinicopathological characteristics are summarized in the table.Forty-six percent had a prior pregnancy; 11 breastfed, 5 diagnosed during pregnancy and 4 during lactation.Most tumors were diagnosed at early stages (I-II, 92.9%), ductal (95.2%), median tumor size 26 mm, and predominantly node-negative.Germline testing was available in 37 patients and identified pathogenic variants in 20.6% (BRCA1/2: 13.8%; PALB2: 3.4%; CHEK2: 3.4%).The most frequent IHC subtype was HR+/HER2-(54.8%),followed by triple-negative (26.2%) and HER2-positive (19.0%).Among HR+/HER2-tumors, Ki67 20% classified 52.2% as luminal B-like.Prosigna testing (n=19) identified luminal B as the predominant intrinsic subtype (52.6%), with 47.4% classified high risk of recurrence.High-risk scores were observed in 71.4% of patients assessed with HER2DX (n=7) and 62.5% with TNBCDX (n=8).Conclusions: Despite frequent early-stage diagnosis and predominance of HR+/ HER2-, with a notable prevalence of triple-negative tumors, molecular profiling revealed high risk of recurrence in a substantial proportion of young women with BC.These findings underscore the biological heterogeneity of YWBC and support integration of molecular tools into clinical decision-making.
Huang et al. (Fri,) studied this question.