导管内癌（DCIS）是一种无侵袭性乳腺肿瘤，占年诊断所有筛查检测发现的乳腺癌的25％。 DCIS中的肿瘤细胞局限于乳腺系统，尽管在一部分患者中，它们可以逃避并进展为浸润性乳腺癌。 DCIS最重要的问题是过度治疗，因为大多数被筛查发现DCIS的患者，即使不进行治疗，也不会出现症状或死于乳腺癌。然而，区分低风险、缓慢增长的DCIS和潜在的进展性DCIS仍然具有挑战性。在本次综述中，我们总结了我们目前对DCIS的了解，并探讨有关DCIS基本生物学的未解之谜，包括有关肿瘤细胞和周围微环境中的基因组事件如何促进DCIS进展为浸润性乳腺癌的问题。此外，我们讨论了会导致缓慢增长DCIS病变过度治疗而不损害高风险患者充分治疗所需的信息。©2022年 Springer Nature Limited。

Ductal carcinoma in situ (DCIS) is a non-invasive breast neoplasia that accounts for 25% of all screen-detected breast cancers diagnosed annually. Neoplastic cells in DCIS are confined to the ductal system of the breast, although they can escape and progress to invasive breast cancer in a subset of patients. A key concern of DCIS is overtreatment, as most patients screened for DCIS and in whom DCIS is diagnosed will not go on to exhibit symptoms or die of breast cancer, even if left untreated. However, differentiating low-risk, indolent DCIS from potentially progressive DCIS remains challenging. In this Review, we summarize our current knowledge of DCIS and explore open questions about the basic biology of DCIS, including those regarding how genomic events in neoplastic cells and the surrounding microenvironment contribute to the progression of DCIS to invasive breast cancer. Further, we discuss what information will be needed to prevent overtreatment of indolent DCIS lesions without compromising adequate treatment for high-risk patients.© 2022. Springer Nature Limited.