乳腺癌（BC）是全球40岁以下女性癌症相关死亡的第二大原因。此外，年轻女性乳腺癌（BCYW）的发病率一直在上升。年轻女性不是筛查计划的重点，而年轻女性的BC倾向于在更晚期被诊断出来。与老年患者相比，这类患者的临床结果和治疗并发症更为严重。与50岁以上妇女相比，BCYW与不同的肿瘤生物学相关，这引起了更糟糕的预后，包括肿瘤恶性程度低、增加Ki-67表达和更多的激素受体阴性肿瘤。相比晚发性BC，癌症易感基因如BRCA1/2的致病变异在早发性BC中更为常见。尽管存在所有这些不同点，但年轻女性的BCYW仍然不为人们所理解，缺乏关于危险因素、诊断、预后和治疗的研究。缺乏面向年轻女性的临床特征或结果数据，目前该亚群体中使用的大多数标准治疗均来自于老年患者。需要更多针对年龄特定的临床数据和治疗选择。在本综述中，我们讨论了年轻女性乳腺癌的流行病学、临床病理学特征、预后、治疗和特殊考虑因素。我们还强调了未来方向，并突出了未来研究需要更多关注的领域。

Breast cancer (BC) is the second leading cause of cancer-related death in women under the age of 40 years worldwide. In addition, the incidence of breast cancer in young women (BCYW) has been rising. Young women are not the focus of screening programs and BC in younger women tends to be diagnosed in more advanced stages. Such patients have worse clinical outcomes and treatment complications compared to older patients. BCYW has been associated with distinct tumour biology that confers a worse prognosis, including poor tumour differentiation, increased Ki-67 expression, and more hormone-receptor negative tumours compared to women >50 years of age. Pathogenic variants in cancer predisposition genes such as BRCA1/2 are more common in early-onset BC compared to late-onset BC. Despite all these differences, BCYW remains poorly understood with a gap in research regarding the risk factors, diagnosis, prognosis, and treatment. Age-specific clinical characteristics or outcomes data for young women are lacking, and most of the standard treatments used in this subpopulation currently are derived from older patients. More age-specific clinical data and treatment options are required. In this review, we discuss the epidemiology, clinicopathologic characteristics, outcomes, treatments, and special considerations of breast cancer in young women. We also underline future directions and highlight areas that require more attention in future studies.