De-Escalating the Extent of Sentinel Lymph Node Biopsy in Patients With Ductal Carcinoma in Situ Undergoing Mastectomy

Background

Sentinel lymph node biopsy (SLNB) for axillary staging in patients with ductal carcinoma in situ (DCIS) undergoing mastectomy is debated due to low nodal positivity rate and risk of morbidity. Standard SLNB entails removing all lymph nodes (LN) that have a radioactive count > 10% of the most radioactive node, contain blue dye or are palpably suspicious. In this study, we hypothesize that judicious SLNB with attempt to remove only the node with the highest radioactive count provides sufficient pathologic information while minimizing morbidity.

Method

A single institution prospective database was retrospectively reviewed to identify women with DCIS who underwent mastectomy and SLNB between 2010 and 2022. Patient characteristics, number of SLNs retrieved, pathologic results and long-term upper extremity complications were analyzed.

Results

A total of 743 LNs were removed in 324 pts. Median (IQR) age was 62 (51-70) years. Dual tracer technique, with technetium-99m labeled radiocolloid and blue dye, was used in 311 (96%) pts, whereas single agent (radioisotope or blue dye alone) was utilized in 9 (2.8%) and 4 (1.2%) patients, respectively. Median (IQR) number of SLN removed was 2 (1-3) (range 1-9). In 99% of cases, the SLN with the highest radioactive count was identified among the first 3 dissected LNs. Final pathology revealed upstaging to invasive cancer in 27.5% (n = 89) of the breasts and nodal positivity in 1.9% (n = 6) of the patients. In all 6 cases, metastatic disease was identified in the LN with highest radioactive count among the LNs retrieved. No additional metastatic nodes were identified after > 3 SLN had been removed. At median follow-up of 57 (range 28-87) months, 8.3% (n = 27) of pts complained of long-term upper extremity symptoms. 7.1% (23 pts) were referred to physical therapy for symptoms such as swelling, fullness, heaviness, stiffness, or sensory discomfort in the upper extremity and/or axillary cording. Long-term upper extremity complications were higher when > 3 SLNs compared to ≤ 3 SLNs were removed (10.4% vs. 6.5%, P = .005).

Conclusion

In this cohort of patients with DCIS undergoing mastectomy who were upstaged on final pathology to node positive invasive cancers, the SLN with the highest radioactive count provided sufficient information for axillary staging. Acknowledging that the “hottest” LN is not always the first 1 removed, these data support an increased likelihood of developing long-term complications when more than 3 SLNs are removed. Rather than comprehensive removal of all SLNs meeting the standard “10% rule,” prioritizing the sequence of removal to the highest count provides the same prognostic information with reduced morbidity.