Intraoperative evaluation of sentinel lymph nodes in invasive lobular carcinoma of the breast.

Background: In breast cancer treatment, sentinel lymph node (SLN) evaluation is used to identify patients who may benefit from axillary lymph node dissection (ALND). Intraoperative evaluation (IE) of SLNs facilitates immediate ALND. Controversy exists regarding the accuracy of intraoperative SLN evaluation for patients with invasive lobular carcinoma (ILC) compared to invasive ductal carcinoma (IDC).

Methods: Using breast cancer registry data from January 2003 to March 2008, the intraoperative SLN evaluation of 66 ILC and 810 IDC patients was compared to the final SLN pathology result and to the performance of ALND.

Results: In ILC, the sensitivities of IE for isolated tumor cells (.2 mm and 2.0 mm, N1a-3a, n = 21) were 0%, 17%, and 71%, respectively. The specificity was 100%. IE identified 16/27 (59%) of SLN-positive (N1mi, N1a-3a) axillae, resulting in synchronous ALND. Delayed ALND for false negative IEs (11/27, 41%) occurred in 7/11 patients (64%). In IDC, the sensitivities of IE for N0(i+) (n = 60), N1mi (n = 75), and N1a-3a (n = 129) metastases were 0%, 7%, and 71%, respectively. The specificity was 99.6%. IE identified 97/204 (48%) of SLN-positive (N1mi, N1a-3a) axillae, resulting in synchronous ALND. Delayed ALND for false negative IEs (107/204, 52%) occurred in 38/107 patients (36%).

Conclusions: Sensitivity and specificity of intraoperative SLN evaluation is very similar in ILC and IDC patients. Intraoperative SLN evaluation facilitated synchronous ALND in concordance with recommended practice guidelines.