Introduction/Background Breast cancer in young women is defined as cancer occurring in a woman under the age of 35. Young age seems to be a negative prognostic factor, with an increased risk of local recurrence and reduced overall survival.

Methodology We carried out a retrospective study, based on files from the Medical Oncology department of the CHU Tlemcen, including patients aged ≤ 35 years old, treated for breast cancer during the year 2020 and 2021. Our objective is to determine the epidemiological, clinical, histological and molecular characteristics.

Results Eighteen patients were included, represent 6% of all cases treated during this period. They were between 30 and 35 years old (94.44%). The majority of patients (12) had a family history of neoplasia including 3 first degree, 11 second degree and beyond and 2 had a history of first degree breast cancer.The diagnosis was mainly made at a localized stage in 15 patients (T1: 4, T2: 12, T3: 2) and only 3 (16.7%) at a metastatic stage. Surgical treatment was performed in 17 patients (11: radical, 5: conservative, 1: palliative). The anatomopathological study revealed mostly invasive ductal carcinoma in 15 patients (83.3%), grade (II: 9 and III: 9), with lymph node invasion in 11 patients (N2: 8, N1: 3, N0: 6). The immunohistochemical study found positive hormone receptors in 13 patients (72.2%) and a HER2 score 3 in 3 patients (16.7%), a luminal B status in 8 patients (44.4%) and triple negative in 4 patients (22.2%). The majority of patients are still alive (16 patients).

Conclusion Breast cancer in young women is a separate entity due to the frequency of neoplastic family history, diagnostic stage and specific molecular profile.