Intra-operative imprint cytology for assessing the sentinel node in breast cancer – Results of its routine use over 8 years

Abstract 

Introduction

Intra-operative imprint cytology (IIC) for analysing sentinel lymph node/s (SLN) in breast cancer allows definitive axillary surgery as a one-step procedure. Most reported studies are research oriented. This study reports long-term results of IIC done as routine clinical practice.

Materials and methods

Eight hundred ninety-six female, operable breast cancer patients underwent SLN biopsy over an 8-year period (January 1999–December 2006). Data were extracted retrospectively from medical records. SLNs were sent intra-operatively to the laboratory where they were bisected, touch imprinted and stained with Hematoxylin & Eosin. Patients with positive IIC had axillary clearance. Formal histological analyses of SLNs were compared with IIC findings. The impact of routine pre-operative axillary ultrasound (introduced in 2003) on IIC sensitivity and specificity was also assessed.

Results

Median age was 61 years (26–89) and median tumour size was 18mm (2–100). A total of 244/896 patients had SLN metastases on final paraffin histology of which 177 were correctly detected by IIC (67 false negatives). 39/67 false negatives could be attributed to sampling error. The overall sensitivity and specificity of IIC for the identification of SLN metastases was 73% and 100%, respectively. The sensitivity of IIC after introduction of pre-operative axillary ultrasound decreased from 75% to 71%.

Discussion

Routine use of IIC for analysis of the SLN in breast cancer allows complete axillary surgery during a single anaesthetic for a majority of patients undergoing SLN biopsy. Almost two thirds of positive axillae were spared a second operation. False negative results are frequent and patients should be warned about the potential need for further axillary surgery.

Keywords: Imprint cytology, Sentinel node biopsy, Breast cancer, Axillary staging