What is the recommended treatment for a woman diagnosed with ductal carcinoma in situ (DCIS)?

Treatment of Ductal Carcinoma In Situ (DCIS)

For most women with DCIS, breast-conserving surgery (lumpectomy) followed by whole-breast radiation therapy is the recommended treatment, with the addition of tamoxifen 20 mg daily for 5 years if the tumor is estrogen receptor-positive. 1, 2

Primary Treatment Options

The three main treatment approaches for DCIS are:

Breast-Conserving Surgery Plus Radiation Therapy (Preferred for Most Patients)

• Lumpectomy followed by whole-breast radiation therapy is the local treatment of choice for most patients with DCIS 3, 1
• This approach reduces local recurrence by approximately two-thirds compared to surgery alone 1
• The NSABP B-17 trial demonstrated that radiation after lumpectomy reduced the 8-year ipsilateral breast tumor recurrence rate from 26.8% to significantly lower levels 3
• Hypofractionated radiation therapy (shorter treatment schedules) is now preferred for most women receiving whole-breast irradiation 1
• Negative surgical margins are critical—margins ≥2 mm are associated with lower recurrence rates compared to margins <2 mm 3
• The specimen must be oriented properly and a specimen radiograph obtained to ensure complete excision of all mammographically detected disease 3, 1
• Post-excision mammography should be performed if the specimen radiograph does not clearly include all microcalcifications 3

Total Mastectomy (For Specific Indications)

• Mastectomy is indicated when: 3, 1
  • Lesions are so large or diffuse that complete excision cannot be achieved without unacceptable cosmesis
  • Multicentric disease is present
  • Persistent positive margins after re-excision, especially with high-grade lesions
  • Prior radiation to the chest/breast (contraindication to further radiation)
  • Patient preference after informed discussion
• Mastectomy achieves cure rates approaching 100%, with only 1-2% of patients experiencing regional or systemic relapse 3
• Subcutaneous mastectomy should NOT be used to treat DCIS 4
• Bilateral mastectomy is not normally indicated for unilateral DCIS 4
• Post-mastectomy radiation therapy is NOT recommended 3

Breast-Conserving Surgery Alone (Highly Selected Cases Only)

• Lumpectomy without radiation may be considered only in highly selected low-risk patients 3, 1
• Strict criteria from Lagios: lesion must be nonpalpable, ≤25 mm in size, detected by mammographic microcalcifications only, clear margins ≥1 mm, and negative postoperative mammography 3
• Even with these strict criteria, the 15-year actuarial local recurrence rate was 18%, with high-grade lesions recurring at 33% 3
• This approach carries substantially higher recurrence risk—population-based data show 10-year recurrence rates of 20% without radiation versus 12.7% with radiation 5
• Approximately 22% of recurrences in women treated without radiation could have been prevented if radiation had been given 5

Axillary Management

• Axillary lymph node dissection is NOT routinely recommended for pure DCIS 3, 4
• Axillary nodal involvement in pure DCIS is rare 3
• Sentinel lymph node biopsy may be considered in specific situations: 3
  • When mastectomy is planned (as future sentinel node procedure would not be possible)
  • When excision is in an anatomic location that could compromise future sentinel node procedure (e.g., tail of breast)
  • When there is high suspicion for occult invasive disease 1

Adjuvant Tamoxifen Therapy

• Tamoxifen 20 mg daily for 5 years should be offered to women with estrogen receptor-positive DCIS 3, 1, 2
• The NSABP B-24 trial demonstrated that tamoxifen after lumpectomy and radiation reduced invasive breast cancer incidence by 43% (relative risk 0.57, p=0.004) 2
• Tamoxifen reduced all breast cancer events (DCIS and invasive) by 37% (relative risk 0.63) 2
• Tamoxifen reduced ipsilateral breast events by 35% and contralateral breast cancer by 48% 2
• The recommended duration is 5 years—there is no evidence that continuation beyond 5 years provides additional benefit 2
• Tamoxifen should be started after completion of radiation therapy, not concurrently, due to potentially increased risk of lung toxicity 3

Essential Pathology Requirements

The pathology report must include: 3, 1

• Specimen orientation and how it was received
• Laterality, quadrant, and type of procedure
• Specimen size in three dimensions
• Histologic features: nuclear grade, presence of necrosis, architectural pattern
• Estimated extent (size) of DCIS
• Location of microcalcifications (in DCIS, benign tissue, or both)
• Margin status—most critical factor: presence or absence of DCIS at margins and distance from margins 3
• Estrogen and progesterone receptor status (for tamoxifen decision-making) 1

Risk Stratification Factors

Higher risk features that influence treatment decisions include: 1

• Age <35 years
• Tumor size ≥2 cm
• High nuclear grade
• Presence of comedo necrosis
• Close or positive surgical margins (<2 mm)
• Estrogen receptor-negative status

Critical Treatment Principles

• Multidisciplinary discussion involving surgeon, pathologist, radiation oncologist, and radiologist is essential before finalizing treatment decisions 3
• Final treatment decisions should not be made until pathological findings have been reviewed and the specimen radiograph compared with the mammogram 3
• Patients must understand that DCIS has an excellent prognosis with either mastectomy or breast-conserving therapy—the impact of local recurrence on overall survival is small 3
• Local recurrence with mastectomy is rare (1-2%), while breast conservation has higher local recurrence rates but does not significantly impact survival 3
• Approximately 50% of recurrences after breast-conserving therapy present as invasive cancer 3, 6
• Most recurrences occur at or near the original lesion site 3

Common Pitfalls to Avoid

• Do not perform routine axillary dissection—this was inappropriately high (37-49%) in historical series and should be avoided 3
• Do not send tissue for frozen section examination—this is not indicated for DCIS 3
• Do not use subcutaneous mastectomy—inadequate for DCIS treatment 4
• Do not omit radiation after breast-conserving surgery unless strict low-risk criteria are met—population data show this leads to preventable recurrences 5
• Do not give adjuvant chemotherapy—there is no role for chemotherapy in pure DCIS management 6