Intraoperative Frozen Section Diagnosis of Sentinel Lymph Node Biopsy Reevaluated.
Shawn P Carey, Timothy M D'Alfonso, Stefano Monni, Sandra J Shin. Weill Cornell Medical College, New York
Background: The purpose of an intraoperative frozen section (FS) consultation at the time of sentinel lymph node (SLN) biopsy in breast cancer patients is to determine the need for axillary lymph node dissection at the time of surgery. It is thought that the cost-benefit ratio of performing an axillary dissection at the time of initial surgery rather than as a second procedure outweighs that of pathology resources and extended surgery time needed to perform a FS. In most instances, however, the FS diagnosis is negative for metastasis. Performing FS only on those patients who have a high likelihood to harbor a positive SLN would increase cost-effectiveness in this clinical scenario. We set out to identify clinicopathologic factors that could predict SLN positivity and therefore help limit FS consultation to a subset of patients intended for a SLN biopsy.
Design: Pathology reports from 350 breast cancer patients' excisions with concurrent SLN biopsies from our institution were reviewed. Tumors were categorized into four histologic groups – invasive ductal carcinoma (IDC), invasive lobular carcinoma (ILC), ductal carcinoma in situ (DCIS), and "Other” for carcinomas of non-IDC, -ILC and –DCIS types. Association of clinical and pathologic factors with SLN metastasis was studied for the entire cohort as well as for individual histologic subgroups.
Results: 75 of 350 (21%) patients had a positive SLN. 24 of the 193 (12%) cases in which an intraoperative FS consultation was performed had SLN metastasis. Tumor size, lymphovascular invasion (LVI), and histologic type were associated with SLN positivity at the 0.05 significance level among all samples. Analysis carried out for each histological group separately revealed the following variables to be significantly associated with SLN metastasis at the 0.05 level: LVI and HER-2/neu overexpression for ILC; patient age for DCIS; multifocality, LVI, tumor size, and histologic grade for IDC. Further analysis for IDC, based on logistic regression using all univariately significant variables, showed that LVI and tumor size remained significant at the 0.05 level after controlling for all other variables.
Conclusions: Only 12% of patients who had a FS performed at the time of SLN biopsy had metastasis. Tumor size and LVI were found to significantly correlate with SLN positivity among all patients studied. Furthermore, we found different factors to be univariately associated with SLN positivity depending on histologic subtype. This information can potentially obviate the need to perform an intraoperative FS on select patients who are likely to have a negative SLN biopsy.
Monday, February 28, 2011 1:00 PM
Poster Session II # 32, Monday Afternoon