Utility of intraoperative frozen section examination of sentinel lymph nodes in ductal carcinoma in situ of the breast.

BACKGROUND: Intraoperative frozen section (IFS) examination of sentinel lymph nodes (SLN) is useful in selecting patients with invasive breast cancer for immediate axillary lymph node dissection. However, whether IFS evaluation of the SLNs in ductal carcinoma in situ (DCIS) of the breast has any value has not been previously assessed.
METHODS: Clinicopathologic data from patients with DCIS who underwent resection with SLN biopsy (2004-2010) were collected to assess the sensitivity, specificity, and accuracy of IFS, and its impact on axillary management.
RESULTS: A total of 267 patients with DCIS underwent resection with SLN biopsy and IFS evaluation. Preoperative pathology was DCIS (n = 231), DCIS with microinvasion (n = 24), and DCIS with other lesions (n = 12). Fifty-two (19.5%) patients had invasive breast cancer on final pathology. SLN metastases were identified in 13 (4.8%) patients; however, only 4 (1.5%) were IFS positive. IFS examination was negative in 263 (98.5%) patients. Among patients with SLN metastases, the most common pattern of metastases was either micrometastasis (n = 6) or immunohistochemistry-positive individual tumor cells (n = 4), whereas 3 patients had a macrometastasis. IFS examination was falsely negative in 9 of these 13 patients for a false-negative rate of 69.3%, and a sensitivity and specificity of 31% and 100% respectively. Nine of the 13 patients underwent axillary lymph node dissection and only 1 patient had further axillary metastasis.
CONCLUSIONS: SLN metastases in DCIS is rare and most commonly involves SLN micrometastasis or immunohistochemistry-positive individual tumor cells. SLN IFS evaluation in DCIS has a low yield and sensitivity, and can be safely omitted to reduce operative duration and cost.