Description

• Ductal carcinoma in situ (DCIS) is a heterogeneous group of premalignant lesions that have the presence of neoplastic, clonal proliferation of noninvasive epithelial cells confined to ducts and lobules.
• 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

• Average annual percentage increase of ~1%
• Estimated 55,720 new diagnoses of DCIS for U.S women in 2023 (1)
• Estimated 51,400 new diagnoses of DCIS for U.S women in 2022
• DCIS accounts for ~80–85% of in situ breast carcinomas (lobular carcinoma in situ [LCIS] accounts for approximately 15–20%) and ~26% 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

• Low-grade DCIS typically expresses estrogen receptor (ER) and progesterone receptor (PR), without HER2 protein overexpression or amplification.
• High-grade DCIS not consistently ER+ or PR+
• BRCA1 and BRCA2 associations observed

Risk Factors

• Female sex, nulliparity, late age at first birth or menopause, first-degree relative with breast cancer, long-term use of postmenopausal combined estrogen and progestin therapy, history of atypical ductal hyperplasia (ADH), dense breast tissue
• Associations with age, BMI, age at menarche, lactation history, oral contraceptive use, and modifiable lifestyle factors (alcohol 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)
  • Screening MMG in women aged <40 years should be based on risk factors.
  • Insufficient evidence regarding benefits and harms of screening MMG if ≥75 years old
  • Insufficient evidence to assess the benefits and harms of digital breast tomosynthesis (DBT) as a primary screening method (I statement)
  • 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 (I statement)
• Clinical breast exam (CBE):
  • USPSTF evidence is insufficient 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.
  • Calcium (1,000 mg) plus vitamin D (1,000 IU) may lower risk of DCIS.
  • 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) may significantly decrease incidence of DCIS in postmenopausal women.