Treatment of Ductal Carcinoma In Situ (DCIS)
The standard treatment for ductal carcinoma in situ (DCIS) includes breast-conserving surgery with radiation therapy or total mastectomy, with consideration of tamoxifen for risk reduction of invasive recurrence. 1
Initial Evaluation and Diagnosis
Complete mammographic evaluation is essential for all suspected DCIS cases
- Standard mediolateral oblique and craniocaudal views
- Magnification views to identify extent of calcifications
- Bilateral mammography required to evaluate contralateral breast 1
Tissue diagnosis is mandatory
- Image-guided core biopsy or open surgical biopsy
- Specimen radiography should be obtained during excision
- Avoid frozen section examination 1
Treatment Algorithm
1. Surgical Options
A. Breast-Conserving Surgery (BCS) + Radiation
- Primary approach for most DCIS patients 1
- Requires wide excision with minimum 5mm margins 2
- Complete removal of all microcalcifications confirmed by post-excision mammography
- NSABP B-24 trial showed 43% reduction in invasive breast cancer with this approach 3
B. Total Mastectomy
- Indicated when:
- Lesions are large or diffuse that cannot be completely removed with acceptable cosmesis
- Persistent involvement of margins, especially with high-grade lesions
- Patient preference 1
- Results in cure rates approaching 100% with only 1-2% relapse rate 1
- Subcutaneous mastectomy should NOT be used to treat DCIS 4
C. Breast-Conserving Surgery Alone
- May be considered in select cases:
- Small, low-grade lesions
- Clear margins of at least 10mm 2
- Low risk of recurrence based on clinical and pathological features
- Studies show higher recurrence rates (6% vs 1.4%) compared to BCS with radiation 2
2. Management of the Axilla
- Axillary surgery (including sentinel node biopsy) should generally NOT be performed for pure DCIS 1
- Exceptions:
- Large DCIS lesions requiring mastectomy where invasion cannot be ruled out
- When there is high suspicion of invasive component
- Sentinel node biopsy should be considered when mastectomy is planned, as it cannot be performed after mastectomy 1
3. Adjuvant Hormonal Therapy
- Tamoxifen should be considered for DCIS patients after BCS and radiation
- FDA approved for DCIS to reduce risk of invasive recurrence 3
- NSABP B-24 trial showed:
- 43% reduction in invasive breast cancer incidence
- Benefit in both ipsilateral (44%) and contralateral (34%) breasts 3
- Standard dosage: 20mg/day for 5 years 3
Risk Stratification Factors
- Nuclear grade (high vs. low)
- Presence of comedo necrosis
- Size of DCIS lesion
- Margin status after excision
- Age of patient
- Estrogen receptor status
Common Pitfalls and Caveats
Underestimation of disease extent: Mammography may underestimate DCIS extent, particularly with larger lesions. Complete imaging workup is essential before definitive surgery 1.
Inadequate margins: Positive or close margins significantly increase recurrence risk. Re-excision should be performed until negative margins are achieved 1.
Overlooking invasive component: Up to 20% of patients diagnosed with DCIS on core biopsy will have invasive carcinoma identified when the entire lesion is removed 1.
Overtreatment concerns: While some DCIS lesions may remain indolent, current clinical tools cannot reliably identify which lesions will progress to invasive cancer, necessitating treatment of all DCIS 5.
Follow-up requirements: All DCIS patients require long-term surveillance with regular mammography regardless of treatment approach 3.
The multidisciplinary approach involving surgeons, radiologists, pathologists, and radiation oncologists is essential for optimal management of DCIS, as it enhances potential for improved outcomes 2, 6.