Is sentinel lymph node (SLN) dissection recommended for patients with ductal carcinoma in situ (DCIS) and comedo necrosis?

Sentinel Lymph Node Dissection for DCIS with Comedo Necrosis

Sentinel lymph node (SLN) dissection is not routinely recommended for patients with ductal carcinoma in situ (DCIS) with comedo necrosis undergoing breast-conserving surgery, but should be considered when mastectomy is planned or when specific high-risk features are present. 1

Recommendations for DCIS with Comedo Necrosis

When SLN Dissection Should Be Considered:

• Mastectomy planned: SLN biopsy should be performed when mastectomy is planned for DCIS with comedo necrosis, as this precludes subsequent SLN biopsy if invasive cancer is found in the mastectomy specimen 1

• Large area of DCIS: Consider SLN biopsy when the area of DCIS by imaging is large (≥5 cm), as this increases the risk of occult invasion 1, 2

• Palpable mass or clinical features suggestive of invasion: Physical examination or imaging showing a mass lesion highly suggestive of invasive cancer warrants SLN biopsy 1

• Comedo necrosis as a specific risk factor: Comedo necrosis is significantly associated with microinvasion (RR=4.1,95% CI=1.6-10.6) and increases the risk of finding invasive disease in the final specimen 3, 4

When SLN Dissection Should Be Avoided:

• Breast-conserving surgery for pure DCIS: For patients with DCIS undergoing breast-conserving surgery without high-risk features, routine SLN biopsy is not recommended 1

• Non-comedo DCIS with clear margins: In pure non-comedo DCIS completely excised with free margins, SLN biopsy should be avoided 5

Evidence Supporting These Recommendations

Risk of SLN Positivity in DCIS

• The risk of having metastatic disease after SLN biopsy for DCIS is estimated at <1%, challenging the case for routinely performing SLN biopsy in all DCIS patients 1

• Meta-analysis results indicate that the mean percentage of positive SLNs is higher in patients with a preoperative DCIS diagnosis (5.95%) than in patients with a postoperative DCIS diagnosis (3.02%) 1

• Systematic reviews show that the pooled estimate of SLN-positivity rate in DCIS is approximately 4.9% (95% CI, 0.042 to 0.055) 1

• In patients with pure DCIS, the prevalence of SLN metastases is low (1.8%), but increases with specific risk factors 5

Risk Factors for Occult Invasion or SLN Positivity

• Two clinicopathological factors significantly associated with having a positive SLN for DCIS are:

  • Presence of tumor necrosis (P=.001) 1, 4
  • Undergoing mastectomy (P=.016) 1

• Additional factors associated with upstaging or SLN positivity include:

  • Larger tumor size (P=.0333) 1, 2
  • Higher grade DCIS (P=.00839) 1
  • Hormone receptor negativity (RR=4.0,95% CI=1.5-11) 3
  • Core needle biopsy diagnosis (versus vacuum-assisted biopsy) 1

Rationale for SLN Biopsy with Mastectomy

• Mastectomy permanently alters the lymphatic drainage pattern to the axilla, making future SLN biopsy technically not feasible 1

• Approximately 25% of patients with seemingly pure DCIS on initial biopsy will have invasive breast cancer at the time of definitive surgical procedure 1, 2

• In patients with DCIS undergoing mastectomy, the rate of finding invasive disease in the final pathology is approximately 30-33% 4

Important Clinical Considerations

• The risk of lymphedema and other complications must be weighed against the potential benefit of SLN biopsy 1

• If SLN is found to be positive in DCIS patients, it is most commonly micrometastatic disease 5, 6

• The upstaging rate from DCIS to invasive disease is approximately 25.8% (95% CI, 0.230 to 0.286) based on meta-analyses 1

• Complete axillary lymph node dissection is not recommended unless there is pathologically documented invasive cancer or axillary lymph node metastatic disease 1

• Postexcision mammography is valuable in confirming adequate excision of DCIS, particularly for patients who initially present with microcalcifications 1

Algorithm for Decision-Making

1. For patients with DCIS with comedo necrosis undergoing mastectomy:

   • Perform SLN biopsy at the time of mastectomy 1, 4

2. For patients with DCIS with comedo necrosis undergoing breast-conserving surgery:

   • If large area (≥5 cm) or other high-risk features (palpable mass, high grade): Consider SLN biopsy 1, 2
   • If small area without high-risk features: SLN biopsy not recommended 1

3. For patients with DCIS with comedo necrosis diagnosed by core biopsy:

   • Higher risk of upstaging to invasive disease; consider SLN biopsy, especially if mastectomy is planned 3, 4