Non-invasive or pre-invasive cancer where the malignant cells are confined to the ducts in the breast and have not spread into the surrounding breast tissue; it is the most common type of non-invasive breast malignancy and currently comprises around 20% of all breast cancers diagnosed

Aetiology

• Risk factors as for breast carcinoma

Pathophysiology

• Malignancy of the ductal tissue of the breast that is contained within the basement membrane
• 20-30% of cases (who do not receive treatment) will develop invasive disease
• Sub-types include comedo, cribriform, micropapillary, and solid types, however most lesions are mixed

Clinical presentation

• Often asymptomatic - detected during screening

Investigations

• Often detected during screening, where it appears as microcalcifications on mammography, either localised or wide spread
• This will then be confirmed on biopsy

Management

• Any detected localised DCIS should be treated with complete wide excision, ensuring the surrounding tissue of all margins have no residual disease
• Adjuvant radiotherapy
• Chemoprevention - endocrine therapy
• Cases of widespread or multifocal DCIS normally requires complete mastectomy

Other ductal precursor lesions

• Epithelial hyperplasia of usual type
• Columnar change (+/- atypia)