DCIS

DCIS, or ductal carcinoma in situ, is a noninvasive form of breast cancer in which abnormal epithelial cells grow within the milk ducts but do not invade beyond the basement membrane. It is considered a noninvasive precursor to invasive ductal carcinoma and is most often detected by screening mammography as clustered microcalcifications. DCIS may be asymptomatic or present as a palpable lump or nipple discharge, but most cases are found before symptoms. In cancer staging, DCIS is classified as stage 0.

Pathology and classification: In DCIS the malignant cells are confined to the ducts. It is graded as low, intermediate, or high based on architectural pattern and nuclear features. Common histologic patterns include cribriform, solid, comedo, papillary, and micropapillary types. High-grade DCIS carries a higher risk of progression to invasive cancer and is more likely to be associated with calcifications.

Diagnosis: Diagnosis is made by image-guided biopsy following suspicious imaging findings. Receptor testing (estrogen receptor, progesterone receptor, HER2) is performed, but receptor status is less central to prognosis than in invasive cancer.

Management: Treatment decisions depend on extent, grade, margins, and patient factors. Breast-conserving therapy—lumpectomy with clear margins followed by whole-breast radiation—is commonly used. Mastectomy may be considered for extensive DCIS. Sentinel lymph node biopsy is typically not required for pure DCIS but may be performed if mastectomy is planned. Endocrine therapy (eg, tamoxifen or aromatase inhibitors) may be offered for ER-positive DCIS to reduce recurrence risk.

Prognosis and follow-up: The prognosis is excellent with treatment. Local recurrence risk varies by grade and margins. Regular imaging, usually including mammography, is recommended after treatment.