Comparative study between ultrasound-guided fine needle aspiration cytology of axillary lymph nodes and sentinel lymph node histopathology in early-stage breast cancer

Interobserver variability between experienced radiologists in evaluating the number of abnormal lymph nodes seen on preoperative axillary ultrasound

AIM

To determine the interobserver variability of experienced radiologists in evaluating the number of suspicious lymph nodes (LNs) seen on axillary ultrasound (AUS) examination, and to evaluate the effects of clinicopathological features on the discordance.

MATERIAL AND METHODS

A prospective non-randomised triple-blind study was conducted from July 2016 to December 2017 at Shanghai Ruijin Hospital. Three experienced radiologists performed AUS on 462 patients (469 axillae) with invasive breast cancer independently and assessed the number of abnormal LNs during the real-time AUS examination. Interobserver agreement was determined according to the kappa statistic.

RESULTS

The mean numbers of metastatic LNs on final histology study were 0.35, 0.98, 3.05 and 4.70 for patients with 0, 1, 2 and >2 abnormal nodes on preoperative AUS. When the cut-off (the number of abnormal LNs seen on AUS was >1) at which the maximal sum of sensitivity and specificity for diagnosis of ≥3 tumour-involved LNs was achieved was applied, the Az values ranged from 0.776 to 0.811. When the number of abnormal LNs was grouped into two-category classification (0-1 versus ≥2 abnormal LNs detected by AUS), good interobserver agreement (kappa: 0.601-0.687) was found, and disagreement between the radiologists was more frequently found in patients with T2-stage tumour and in those with one or two tumour-involved nodes.

CONCLUSION

Abnormal LN count according to two-category classification (0-1 versus ≥2 abnormal LNs detected by AUS) was a feasible method with good accuracy and high repeatability to select patients with heavy nodal disease in the post-Z0011 trial era.

Gamma probe and ultrasound-guided fine needle aspiration cytology of the sentinel node (GULF) trial

PURPOSE

Sentinel lymph node biopsy (SLNB) was introduced as a minimally invasive technique for nodal staging. Since associated morbidity is not negligible, it is highly relevant to pursue a more minimally invasive alternative. The purpose of this study was to prospectively evaluate the sensitivity of fine needle aspiration cytology (FNAC) with combined gamma probe and ultrasound (US) guidance in comparison with the gold standard histology of the sentinel node (SN) after SLNB for detecting metastasis.

METHODS

The study was designed as a prospective, multicentre, open-label, single-arm trial enrolling patients with newly diagnosed cutaneous melanoma or breast cancer between May 2015 and August 2017. Sample radioactivity was measured using a Mini 900 scintillation monitor. After FNAC, all patients underwent SLNB. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were estimated.

RESULTS

Accrual was terminated early following an unplanned interim analysis indicating that a FNAC sensitivity of at least 80% could not be achieved. In total 58 patients of the originally planned 116 patients underwent FNAC with gamma probe and US guidance. There were no true-positive FNAC results, 14 false-negative results and one false-positive result, and thus the sensitivity, specificity, PPV and NPV of FNAC were 0%, 98%, 0% and 75%, respectively. At least 75% of the FNAC samples had a radioactivity signal higher than the background signal.

CONCLUSION

FNAC with gamma probe and US guidance is not able to correctly detect metastases in the SN and is therefore not able to replace SLNB. Gamma probe-guided US is a highly accurate method for correctly identifying the SN, which offers possibilities for future research.