Is there any utility to frozen section or immunohistochemistry examination of the sentinel lymph node (SLN) in patients with ductal carcinoma in situ (DCIS)?

Abstract

1091 Background: Whether SLN biopsy (SLNB) should be performed in patients with DCIS is controversial. Many centers perform SLNB in DCIS believing it obviates the need for re-operation for axillary staging when invasive cancer (IC) is discovered. Given the low incidence of occult IC detected, whether intra-operative pathologic evaluation during SLNB in DCIS patients provides value has not been addressed. Methods: Demographic and clinico-pathologic data was collected and analyzed for all patients undergoing surgical resection for DCIS between 2004-2010 in order to determine the sensitivity, specificity and accuracy of frozen section (FS) and immuno-histochemistry (IHC) examination of the SLN, and its’ impact on axillary management. Results: 267 DCIS patients (median age 57 years) underwent lumpectomy (N=72) or mastectomy (N=195) with SLNB, intra-operative FS and IHC evaluation. Pre-operative pathology was DCIS (N=231), DCIS with micro-invasion (< 2 mm, N= 24) and DCIS associated with other lesions (N=12). SLN metastasis (SLNM) was identified in 13 patients (4%), of which only 4 were FS positive (1%). SLN micrometastasis (≤ 2 mm) and individual tumor cells (ITCs) were detected by IHC in 10 of 13 patients, while 3 patients had macro-metastasis. Overall, 50 patients (19%) had IC on final pathology. The FS was falsely negative in 9 patients (7%), and had sensitivity, specificity and accuracy of 31%, 100% and 98% respectively in identifying SLNM. 8 of 13 patients with SLNM underwent axillary lymph node dissection (ALND) of which only 1 patient (with macro-metastasis) had further axillary metastasis. On a need to treat basis, 30 and 91 patients would have to undergo FS and IHC exam respectively to identify 1 patient with a metastasis. Conclusions: SLN metastasis in DCIS is uncommon and the prognostic significance of micro-metastasis or ITCs in DCIS is unknown. Given the infrequent higher axillary nodal involvement and low sensitivity and yield of FS and IHC evaluation in DCIS particularly for identifying candidates for ALND, these procedures can be safely omitted thereby reducing operative time and cost. Additional studies are needed to validate these results.