What are the treatment options for ductal carcinoma in situ (DCIS) of the breast?

Treatment of Ductal Carcinoma In Situ (DCIS)

Breast conservation therapy (wide local excision with radiation) is the standard treatment for most DCIS cases, while tamoxifen should be added for ER-positive DCIS to reduce recurrence risk. 1

Surgical Options

Breast-Conserving Surgery (BCS)

• First-line approach for most DCIS cases when:
  • Tumor size is small relative to breast size
  • Clear margins can be achieved
  • Unifocal disease is present
• Requires complete removal of the lesion with negative margins
  • Margins ≥2mm are considered adequate
  • Margins <1mm are inadequate and require re-excision 1
• Specimen radiography should be performed to confirm complete removal of calcifications
• Post-excision mammogram is essential to document complete removal 1

Mastectomy

• Reserved for specific situations:
  • Multicentric disease
  • Large tumors (>3-4cm) in small breasts
  • Positive margins after attempts at re-excision
  • Patient preference 1
• Following mastectomy, the risk of recurrence is extremely low 2

Radiation Therapy

• Strongly recommended after BCS for all DCIS subgroups 1
• Reduces local recurrence risk by approximately 50% 2
• Standard dose: 45-50 Gy at 1.8-2.0 Gy per fraction 1
• Boost to tumor bed (to 60-66 Gy) may be considered for:
  • Close margins
  • High-grade lesions
  • Younger patients 1
• Omission of radiation may be considered only in very low-risk cases:
  • Small tumors (<10mm)
  • Low/intermediate nuclear grade
  • Wide negative margins 1

Hormonal Therapy

• Tamoxifen is indicated for ER-positive DCIS after BCS (with or without radiation) 1
• Reduces risk of:
  • Ipsilateral recurrence by approximately 25%
  • Contralateral breast cancer 3
• Standard dose: 20mg daily for 5 years 3
• Should NOT be used in ER-negative disease as it may be detrimental 1

Axillary Management

• Sentinel lymph node biopsy is NOT routinely recommended for DCIS 1
• Exceptions where sentinel node biopsy should be considered:
  • Large, high-grade DCIS requiring mastectomy (due to risk of occult invasion)
  • Clinical suspicion of invasion
  • Lesions >3cm 1
• Nodal irradiation is unnecessary for patients with DCIS 1

Follow-up Care

• Regular clinical examinations:
  • Every 6 months for years 1-5
  • Annually thereafter 1
• Annual mammography of both breasts
• No need for routine tests (bone scan, chest x-ray, CT scan, liver function tests) in asymptomatic patients 1

Special Considerations

Risk Factors for Recurrence

• Age <50 years at diagnosis
• High nuclear grade
• Comedo-type necrosis
• Tumor size >25mm
• Close or positive margins 2

Common Pitfalls to Avoid

1. Inadequate margin assessment - ensure proper orientation and marking of specimens
2. Failure to perform post-excision mammography - essential to confirm complete removal
3. Unnecessary axillary dissection - nodal involvement is rare in pure DCIS
4. Overtreatment of low-risk DCIS - consider risk factors when planning therapy
5. Underestimation of invasive component - up to 20% of image-guided biopsies diagnosed as DCIS will have invasive carcinoma when completely excised 1

The treatment of DCIS has evolved toward less aggressive approaches while maintaining excellent outcomes, with 10-year breast cancer-specific survival rates of 97-98% 4. Treatment decisions should be based on tumor characteristics, extent of disease, and patient factors to optimize outcomes while minimizing unnecessary interventions.