What are the treatment options for DCSI (Disease/Condition/Syndrome/Intervention)?

Treatment of Ductal Carcinoma In Situ (DCIS)

For DCIS, breast-conserving surgery (BCS) with whole-breast radiation therapy is the preferred treatment approach, achieving local control rates equivalent to mastectomy while preserving the breast, with adjuvant endocrine therapy recommended for hormone receptor-positive disease to reduce ipsilateral and contralateral recurrence risk. 1

Surgical Management

Primary Surgical Options

• BCS is the treatment of choice for most patients with DCIS, provided clear resection margins can be achieved 1
• Negative margins of at least 2 mm are required to minimize local recurrence risk 2
• Mastectomy is indicated for:
  • Widespread disease involving ≥2 quadrants 1
  • Extensive or multicentric DCIS 1
  • Cases where negative margins cannot be achieved with BCS 1, 3
  • Patient preference 1

Lymph Node Management

• Axillary lymph node dissection is NOT routinely recommended for pure DCIS 1
• Sentinel lymph node biopsy (SLNB) should be considered only if:
  • Mastectomy is planned 2, 3
  • The lesion location could compromise future lymphatic drainage patterns 2
• Approximately 5% of patients with DCIS on core needle biopsy will have positive sentinel nodes, and 1% may be upgraded to metastatic disease 4

Margin Assessment

• Re-excision is required if margins are less than 2 mm after initial surgery 2
• Postexcision mammography is valuable to confirm adequate excision, particularly when microcalcifications were present on initial imaging 2, 3

Radiation Therapy

Indications and Benefits

• Whole-breast radiation therapy (WBRT) after BCS reduces ipsilateral breast tumor recurrence by 50-70% 1, 2, 3
• WBRT does not improve overall survival but significantly decreases local recurrence rates 1, 5
• Radiation therapy is particularly important for high-risk features including comedo necrosis, high nuclear grade, and younger age 3, 5

Radiation Boost Considerations

• Boost radiation to the tumor bed is recommended for non-low-risk DCIS, especially in patients aged ≤50 years 1, 2
• Boost may be omitted in low-risk scenarios (grade 1 tumor with <25% DCIS component) 2

Omission of Radiation Therapy

• Radiation may be considered for omission ONLY in women >70 years of age with ALL of the following low-risk features 2:
  • Grade 1 histology
  • Limited DCIS component (<25%)
  • Negative margins ≥2 mm
  • Small tumor size
• Do not omit radiation based solely on low-grade features without considering all risk factors including age, margin status, and tumor size 2, 3

Adjuvant Endocrine Therapy

Hormone Receptor-Positive DCIS

• ER testing is recommended for all newly diagnosed DCIS to determine potential benefit of endocrine therapy 1
• Both tamoxifen and aromatase inhibitors (AIs) may be used after local breast-conserving treatment to prevent local recurrence and decrease risk of second primary breast cancer 1

Specific Recommendations by Menopausal Status

• For premenopausal women: Tamoxifen is the standard endocrine therapy option 1, 2
• For postmenopausal women: Either tamoxifen or AI are acceptable options, though tamoxifen is often favored based on side-effect profile 2

Evidence for Benefit

• Tamoxifen reduces the incidence of all new breast events in excised DCIS treated with radiation therapy 1
• In the NSABP B-24 trial, tamoxifen showed significant reduction in relative risk of subsequent breast cancer restricted to ER-positive DCIS (HR 0.49; P=0.001) at 10 years 1
• Endocrine therapy reduces both ipsilateral recurrence and contralateral disease in hormone receptor-positive DCIS 1, 2

Post-Mastectomy Considerations

• Following mastectomy for DCIS, tamoxifen or AIs might be considered to decrease the risk of contralateral breast cancer in patients with high risk of new breast tumors 1

Progesterone Receptor Testing

• PgR testing is considered optional for DCIS, as there are no data supporting prognostic or predictive value independent of ER 1
• ER alone is more predictive than combined ER/PgR status for tamoxifen benefit 1

Risk Stratification and Prognostic Factors

High-Risk Features Requiring More Aggressive Treatment

• Comedo necrosis is an independent predictor of ipsilateral breast tumor recurrence 3, 5
• High nuclear grade (grade 3) 3, 5
• Younger age at diagnosis (<50 years) 1, 5, 4
• Larger tumor size 5, 4
• Positive or close surgical margins (<2 mm) 5, 4

Low-Risk Features

• Grade 1 tumors with limited DCIS component (<25%) are considered low-risk with excellent prognosis 2
• Older age (>70 years) 2
• Small tumor size 2
• Negative margins ≥2 mm 2

Treatment Algorithm Based on Disease Extent and Risk

Limited Disease with Low-Risk Features

• BCS with negative margins ≥2 mm 2
• WBRT (may be omitted only in women >70 years with all low-risk features) 2
• Adjuvant endocrine therapy if ER-positive 2

Limited Disease with High-Risk Features (Comedo Necrosis, High Grade)

• BCS with negative margins ≥2 mm 3
• WBRT with boost to tumor bed 3
• Adjuvant endocrine therapy if ER-positive 3

Extensive or Multicentric Disease

• Mastectomy without lymph node dissection 1
• Consider SLNB at time of mastectomy 2, 3
• Adjuvant endocrine therapy if ER-positive to reduce contralateral breast cancer risk 1

Follow-Up Recommendations

• Interval history and physical examination every 6-12 months for 5 years, then annually 1, 3
• Annual diagnostic mammography of both breasts (or contralateral breast if mastectomy performed) 1, 3
• For patients on tamoxifen: Annual gynecologic assessment if uterus is present 6
• For patients on AIs: Monitor bone health with bone mineral density determination at baseline and periodically 6

Critical Pitfalls to Avoid

• Do not perform axillary lymph node dissection routinely for pure DCIS 1
• Do not omit radiation therapy based solely on low-grade features without considering all risk factors 2, 3
• Do not accept margins <2 mm without attempting re-excision 2
• Recognize that approximately 25-50% of local recurrences after breast-conserving therapy for DCIS present as invasive cancer 3, 5
• Be aware that about 25% of patients with seemingly pure DCIS on initial biopsy will have invasive breast cancer at definitive surgery 2, 3
• Do not use combination of olaparib and capecitabine in patients with gBRCAm 1

Special Considerations

Genetic Risk Assessment

• Genetic counseling should be recommended if the patient is considered high risk for hereditary breast cancer 1
• Risk-reducing bilateral mastectomy may be offered to women with BRCA1/2 mutations 1

Reconstruction Options

• Breast reconstruction, preferably immediate, should be available to women requiring mastectomy 1
• Silicone gel implants are safe and acceptable 1

Monitoring for Immune-Related Adverse Events

• Patients receiving pembrolizumab should be monitored very closely for immune-related adverse events throughout treatment 1