Ductal Carcinoma In Situ

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Description

  • Ductal carcinoma in situ (DCIS) is a heterogeneous group of malignant lesions with neoplastic, clonal proliferation of noninvasive epithelial cells confined to the milk ducts.
  • Comprises 1 in 4 cases of all newly diagnosed breast cancers
  • Mortality from DCIS with subsequent progression to invasive breast carcinoma (IBC) is low (<1%), regardless of histologic type or treatment.

Epidemiology

Incidence

  • Estimated 59,080 new diagnoses of DCIS for US women in 2025 (1)
  • DCIS accounts for ~80–85% of in situ breast carcinomas (lobular carcinoma in situ [LCIS] accounts for approximately 15–20%) and ~25% of all new breast cancers.
  • Increase in incidence with increase in age; rate of DCIS doubles from age range of 40 to 49 years to 70 to 84 years.

Etiology and Pathophysiology

Genetics

BRCA1 and BRCA2 has been associated with DCIS, but with a lower strength of association compared to invasive breast cancer.

Risk Factors

  • Female sex, nulliparity, late age at first birth or menopause, older age, first-degree relative with breast cancer, long-term use of postmenopausal combined estrogen and progestin therapy, history of atypical ductal hyperplasia (ADH), obesity, alcohol use, dense breast tissue
  • Associations with age at menarche, lactation history, oral contraceptive use, and smoking remain unclear.

General Prevention

  • Screening may result in overdiagnosis with little or no reduction in the incidence of advanced cancers.
  • General screening guidelines—U.S. Preventive Services Task Force (USPSTF):
    • Biennial mammography (MMG) for women aged 40 to 74 years (B recommendation)
    • Insufficient evidence regarding benefits and harms of screening MMG if ≥75 years old
    • Current evidence suggests that both digital MMG and digital breast tomosynthesis (DBT) are effective primary screening modalities.
    • Insufficient evidence to assess the balance of benefits and harms of adjunctive screening using breast ultrasonography, magnetic resonance imaging (MRI), DBT, or other methods in women identified to have dense breasts on an otherwise negative screening mammogram
  • Clinical breast exam (CBE):
    • USPSTF does not address the CBE in its most recent 2024 screening guideline, but previous 2019 guidelines stated that there is insufficient evidence to assess benefits and harms when added to MMG screening for women aged ≥ 40 years.
    • WHO states CBE may be beneficial in settings with weak health settings (MMG not accessible) for women 50 to 69 years old.
  • Risk reduction:
    • Limit alcohol intake to <1 drink per day, exercise, maintain a healthy diet, and weight control.
    • Hormonal risk reduction agents recommended in certain high-risk women ≥35 years old; tamoxifen for premenopausal women and raloxifene for postmenopausal women
    • Anastrozole (an aromatase inhibitor) significantly decreases incidence of DCIS in postmenopausal women.

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