Treatment of Ductal Carcinoma In Situ (DCIS)
For ductal carcinoma in situ (DCIS), surgical excision with clear margins is the standard treatment, which may be followed by radiotherapy depending on risk factors.
Diagnosis and Initial Assessment
DCIS is characterized by proliferation of malignant epithelial cells that remain confined within the ductal system without invasion through the basement membrane. Key diagnostic features include:
- Histologically: Proliferation of cells with hyperchromatic nuclei and scant cytoplasm
- Radiographically: Often presents as microcalcifications on mammography
- Pathologically: Requires confirmation of non-invasion through basement membrane
Treatment Algorithm
Step 1: Surgical Management
Breast-conserving surgery (BCS) is the standard approach for most DCIS cases 1
- Complete excision with clear margins is essential
- Radiologically proven complete excision should be confirmed 1
- Post-excision mammography should be performed to confirm removal of all microcalcifications
Modified radical mastectomy is indicated when:
- Extensive microcalcifications are present at diagnosis
- Clear margins cannot be achieved with BCS
- Patient preference (after appropriate counseling)
Step 2: Margin Assessment
- Clear margins: Defined as no tumor cells at the inked margin
- Involved margins: Require re-excision or mastectomy 1
- Close margins: Consider re-excision based on extent and distribution of DCIS
Step 3: Adjuvant Therapy
Radiotherapy:
- Standard after breast-conserving surgery to reduce local recurrence 1
- May be omitted in select low-risk cases (small size, wide margins, low grade)
Hormonal therapy:
- Consider tamoxifen or aromatase inhibitors for ER-positive DCIS to reduce recurrence risk
Special Considerations
Risk Stratification
Low-risk DCIS:
- Small size (<2.5 cm)
- Low or intermediate grade
- Wide surgical margins (>10 mm)
- Age >50 years
High-risk DCIS:
- Large size (>2.5 cm)
- High grade with comedo necrosis
- Close or positive margins
- Young age (<40 years)
Surveillance After Treatment
- Regular clinical examination every 6-12 months for 5 years, then annually
- Annual mammography of both breasts
- MRI may be considered for select high-risk patients
Common Pitfalls to Avoid
Underestimating extent of disease: DCIS can be more extensive than apparent on imaging; careful preoperative assessment is crucial
Inadequate margins: Positive margins significantly increase recurrence risk; re-excision should be performed until negative margins are achieved
Overtreatment of low-risk DCIS: Not all DCIS requires aggressive therapy; consider risk factors when determining need for radiotherapy or hormonal therapy
Inadequate pathologic assessment: Ensure thorough sampling to exclude invasive components that would alter management
The treatment of DCIS has evolved significantly, with a trend toward less aggressive approaches for low-risk disease while maintaining excellent outcomes. The primary goal remains complete surgical excision with clear margins, with adjuvant therapy decisions based on individual risk factors for recurrence and progression to invasive disease.