[3] It rarely produces symptoms or a breast lump that can be felt, typically being detected through screening mammography.

In situ means "in place" and refers to the fact that the abnormal cells have not moved out of the mammary duct and into any of the surrounding tissues in the breast ("pre-cancerous" indicates that it has not yet become an invasive cancer).

DCIS has been classified according to the architectural pattern of the cells (solid, cribriform, papillary, and micropapillary), tumor grade (high, intermediate, and low grade), or the presence or absence of comedo histology;[8] or, in the case of the apocrine cell-based in situ carcinoma, apocrine ductal carcinoma in situ, it may be classified according to the cell type forming the lesion.

[14] Clinically, DCIS is considered to be a premalignant (i.e. potentially malignant) condition,[15] because the biologically abnormal cells have not yet crossed the basement membrane to invade the surrounding tissue.

[14][16] When multiple lesions (known as "foci" of DCIS) are present in different quadrants of the breast, this is referred to as "multicentric" disease.

Women considered at higher risks are those who have a family history of breast cancer, those who have had their periods at an early age or who have had a late menopause.

[22] Nonetheless, the risk of developing noninvasive cancer increases with age and it is higher in women older than 45 years.

[28] Surgical removal, with or without additional radiation therapy or tamoxifen, is the recommended treatment for DCIS by the National Cancer Institute.

[33] While the authors caution that longer follow-up will be required before a definitive conclusion can be reached regarding long-term toxicity, they point out that ongoing technical improvements should further restrict radiation exposure in healthy tissues.

[7][37] Mastectomies remain a common recommendation in those with persistent microscopic involvement of margins after local excision or with a diagnosis of DCIS and evidence of suspicious, diffuse microcalcifications.

[38] Some institutions that have encountered high rates of recurrent invasive cancers after mastectomy for DCIS have endorsed routine sentinel node biopsy (SNB).

[44] Biomarkers can identify which women who were initially diagnosed with DCIS are at high or low risk of subsequent invasive cancer.