The issue of overdiagnosis and overtreatment of lesions detected by breast screening mammography has been debated in both international media and the scientific literature. A proportion of cancers detected by breast screening would never have presented symptomatically or caused harm during the patient’s lifetime. The most likely (but not the only) entity which may represent those overdiagnosed and overtreated is low-grade ductal carcinoma in situ (DCIS). In this article, we address what is understood regarding the natural history of DCIS and the diagnosis and prognosis of low-grade DCIS. However, low cytonuclear grade disease may not be the totality of DCIS that can be considered of low clinical risk and we outline the issues regarding active surveillance vs excision of low-risk DCIS and the clinical trials exploring this approach.

国际媒体和科学文献中一直对乳腺筛查乳房 X 光检查检测到的病变过度诊断和过度治疗的问题存在争议。通过乳房筛查发现的一部分癌症在患者一生中永远不会出现症状或造成伤害。最有可能（但不是唯一）代表过度诊断和过度治疗的实体是低级别导管原位癌（DCIS）。在本文中，我们将阐述对 DCIS 自然史以及低级别 DCIS 的诊断和预后的了解。然而，低细胞核级别疾病可能并不是可被视为低临床风险的 DCIS 的全部，我们概述了有关低风险 DCIS 的主动监测与切除的问题以及探索这种方法的临床试验。