P3-07-31: Intra-Operative Assessment of Sentinel Lymph Nodes in Breast Cancer with Touch Imprint Cytology (TIC) in 460 Consecutive Patients

Background

Sentinel node biopsy (SNB) accurately predicts the axillary lymph node status in patients with breast cancer. The sentinel lymph node (SLN) is evaluated by routine histology, requiring 3–5 days for the results and a second operation if the SLN is positive. However a second operation can be avoided if a reliable intraoperative assessment of the SLN was available. The techniques used for intra-operative assessment of the SLN include frozen section, touch imprint cytology (TIC) and more recently molecular biology assays. The aim of this study was to evaluate the accuracy of TIC in the assessment of the SLN.

Methods: A prospective study to include 460 patients with breast cancer who underwent SNB and had the sentinel node assessed intra-operatively with TIC. The SLN was bisected and a touch imprint was made on to a slide. The imprint was stained with Giemsa stain. Permanent sections were evaluated with H&E and immunohistochemical staining. The TIC results were compared with the final histology of the SLN.

Results: 766 SLN's were harvested from 460 patients (Mean - 1.66). Of the 460 patients, TIC was falsely negative in 50(24%) patients. No patients had false positive results. Negative predictive value was 87%. The accuracy rate was 89%. 94 patients were positive on histology. TIC was positive in 44 patients and negative in 50. The sensitivity, specificity and positive predictive value of TIC was 47%, 100% and 100% respectively. By acting on the results of TIC, 44 patients (47%) had an axillary clearance at the primary operation and were thus spared a second operation.

Conclusion: TIC in our cohort of 460 patients and 766 sentinel lymph nodes had an accuracy rate of 89% and specificity of 100%. Our study compares favourably with published literature, confirming that TIC is a simple, quick, reliable and reproducible technique that can be used for intra operative assessment of the SLN. A sensitivity of 47% means that about half of the SLN positive patients were spared a second operation. We had hoped that with more experience, our sensitivity would improve but since this has not been the case we are now moving towards molecular biology assays (OSNA) to assess the SN intra-operatively.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-31.