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Ductal Carcinoma in Situ (DCIS)

Basics

Description

  • Noninvasive neoplastic proliferation of epithelial cells within breast ducts/lobules

  • Represents ~25% of all breast cancers

  • Confined to ducts/lobules, does not invade basement membrane

  • Mortality <1% from progression to invasive carcinoma

  • Frequently detected via screening mammography

Epidemiology

  • Estimated U.S. cases: 55,720 (2023); 51,400 (2022)

  • Accounts for:

    • 80–85% of in situ breast carcinomas

    • ~26% of new breast cancer diagnoses

  • Risk doubles from age 40–49 to 70–84

  • Slight annual increase (~1%)

Etiology & Pathophysiology

Molecular Profile

  • Low-grade DCIS: ER/PR+, HER2−

  • High-grade DCIS: variable ER/PR status

  • BRCA1/2 associations noted

Risk Factors

  • Nonmodifiable:

    • Female sex

    • Family history

    • Nulliparity

    • Late menopause

    • Prior atypical ductal hyperplasia (ADH)

    • Dense breast tissue

  • Modifiable (less clear):

    • Alcohol

    • Obesity/BMI

    • Smoking

    • Hormone therapy (estrogen + progestin)

Prevention

Screening (USPSTF)

  • Biennial mammography (age 40–74)

  • Individualized screening <40 yrs

  • No clear benefit ≥75 yrs

Chemoprevention

  • Tamoxifen: premenopausal

  • Raloxifene/anastrozole: postmenopausal

  • Vitamin D + calcium may help

Diagnosis

Physical Exam

  • Look for asymmetry, nipple changes, discharge, palpable mass

  • Examine lymph nodes (axillary, supraclavicular)

Differential Diagnosis

  • ADH, LCIS, papillomas, hyperplasia, flat epithelial atypia, Paget’s disease

Imaging

  • MMG: microcalcifications (most common presentation)

  • BI-RADS classification essential:

    • 0 = incomplete, 1 = negative, 2 = benign

    • 3 = probably benign (<2% risk)

    • 4 = suspicious (biopsy likely)

    • 5 = highly suggestive of malignancy

    • 6 = biopsy-proven malignancy

MRI (High-risk groups)

  • BRCA mutations

  • Thoracic radiation (age 10–30)

  • Genetic syndromes (e.g. Li-Fraumeni, PTEN)

  • ≥20% lifetime risk based on models

Pathology

  • Core needle or vacuum-assisted biopsy (image-guided)

  • Histologic grade: low/intermediate/high

  • Architectural types: comedo, cribriform, solid, papillary, micropapillary

  • ER/PR status determination critical

Treatment

Surgical Options

  • Breast-conserving surgery (lumpectomy) ± radiation

    • Sentinel lymph node biopsy if future lymph mapping might be compromised

  • Total mastectomy (if margins unclear or multicentric disease)

    • ± sentinel node biopsy

  • Axillary dissection not indicated unless invasive disease present

Radiation Therapy

  • Reduces recurrence by ~50%

  • No overall survival benefit

  • Not always necessary (consider Oncotype DX DCIS score)

Chemoprevention (ER+ only)

  • Tamoxifen: premenopausal

  • Tamoxifen or AI: postmenopausal

  • Duration: 5 years

  • No role for adjuvant chemotherapy

Prognosis

  • 10-year survival >95%

  • Recurrence risk:

    • After mastectomy: 1–2%

    • After lumpectomy: higher, esp. with:

      • Age <40

      • High nuclear grade/comedo necrosis

      • Close/positive margins

  • ER+ tumors = lower recurrence

Oncotype DX DCIS Score

  • <39 = low risk: radiation unlikely to help

  • 39–54 = intermediate risk

  • 55–100 = high risk: radiation likely beneficial

Follow-Up

  • Physical exam: every 6–12 months (first 5 years), then annually

  • MMG: yearly; first at 6–12 months after BCT

  • Monitor tamoxifen/AI use per guidelines

Clinical Pearls

  • DCIS is noninvasive but precancerous

  • Detection increased due to widespread MMG

  • Treatment aims to prevent IBC and recurrence

  • Oncotype DX helps decide need for radiation

  • Most patients do well with conservative surgery ± radiation