Molecular Profile of Breast Cancer in Young Women Under 40 Years: Experience from the Oncology-Radiotherapy Department of Mohammed VI University HospitaL Marrakech, Morocco

Breast cancer in young women is relatively uncommon but often exhibits aggressive biological and clinical characteristics. The molecular landscape of these tumors remains poorly described in North African populations. This study aimed to characterize the molecular profile of breast cancer in young women in the Marrakech region of Morocco and to evaluate its correlation with clinicopathological features and prognostic implications. We conducted a retrospective analysis of breast cancer cases diagnosed and treated at the Oncology-Radiotherapy Department, Mohammed VI University Hospital Center of Marrakech. Data were extracted from institutional records January 2018 and December 2024, with a specific subgroup of women younger than 40 years. Clinical, pathological, therapeutic, and immunohistochemical data (ER, PR, HER2, Ki-67) were analyzed, and molecular subtypes were classified according to St. Gallen 2015 guidelines. Associations between molecular subtypes, treatment modalities, recurrence, metastasis, and survival were assessed. Young women accounted for 10.7% of breast cancer cases (mean age 34 years). Molecular classification showed a predominance of Luminal B (42.1%), followed by Luminal A (23%), HER2-enriched (20%), and Triple-negative (14.5%). Aggressive subtypes (HER2-enriched and triple-negative) were associated with high grade (SBR III, 64%-68%), larger tumor size (T2–T3, 70-72%), lymph node invasion (65%), vascular emboli (26-28%), and higher rates of distant metastasis at diagnosis (HER2-enriched 18%, Triple-negative 20%). Recurrence was highest in TNCB (48%) and HER2-enriched (42%) tumors.