The Role of Combined Assessment in Preoperative Axillary Staging

INTRODUCTION

Axillary lymph node status is the single most significant prognostic factor in breast cancer,¹ and during the last decade, sentinel lymph node biopsy has become the gold standard procedure to determine lymph node status.² This approach allows selection of patients who should directly undergo axillary lymph node clearance, sparing a second surgical procedure.³ Sentinel lymph node biopsy is indicated for patients with normal preoperative axillary lymph nodes. Imaging assessment of axillary lymph nodes involves preoperative staging with axillary ultrasound scan (AUS). Although many studies report the use of positron emission tomography (PET) and magnetic resonance imaging (MRI) in preoperative staging, AUS remains the standard imaging modality in the preoperative staging of axillary lymph nodes in the United Kingdom.⁴ We report our experience with the use of AUS in detecting metastatic lymph nodes preoperatively.

RESULTS

In the 219 women included in the study, 228 invasive breast cancers were diagnosed; 9 patients had bilateral breast cancer. The patients' mean age was 60 years (range 29-90 years).

The final histology report revealed 49 (21.5%) cases with metastatic axillary lymph nodes. Of the 49, preoperative axillary staging detected metastatic axillary lymph nodes in 22 cases. Patients with these cancer cases were primarily offered axillary lymph node clearance. Preoperative axillary staging failed to detect metastatic axillary lymph nodes in 27 of the 49 cases. These cancer cases were elected initially for sentinel lymph node biopsy that revealed the metastatic lymph nodes (Table 1).

Preoperative AUS was reported as U1/U2, U3, and U4/U5 in 19 (38.8%), 14 (28.6%), and 16 (32.7%) cancer cases, respectively (Table 1).

DISCUSSION

In the last 3 decades, the management of axillary lymph nodes in patients with breast cancer has changed remarkably. More recently, the ACOSOG Z0011 trial has been described as practice changing.^5,6 More emphasis is placed on accurate preoperative axillary staging to determine lymph node status and to plan surgery accordingly.

AUS is the gold standard method for preoperative staging in the United Kingdom because of its high sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy.³ The results of various studies are shown in Table 6.

Although ultrasound is the best evaluated modality, centers around the world have used other imaging modalities such as MRI,¹¹ computed tomography,¹² duplex sonography,¹¹ 99mTc-sestamibi scintimammography^11,12 and PET.^11-13 These methods have not been routinely adopted because they are not uniformly available.¹⁴ Scan of the axilla is noninvasive and fast¹⁵ although the technique is operator and equipment dependent.⁷

Combining clinical examination, AUS, and FNA increases the accuracy of diagnosing metastatic lymph nodes and reduces the number of sentinel lymph node biopsies.^1,16 The diagnostic features of AUS suggesting malignancy are thickening of cortex and absence of hilum.¹⁴ These 2 findings carried a positive predictive value of 100% in the Torres Sousa et al 2011 study.¹⁷

Many studies emphasize the importance of combined assessment in determining lymph node status. Gruber et al estimated that 40% of patients with breast cancer received overtreatment with unnecessary axillary lymph node clearance if preoperative staging included clinical examination and/or imaging (AUS) only.¹⁸ Some studies show that performing an ultrasound-guided FNA on 2 or more lymph nodes will increase the sensitivity 47.1%-80% and negative predictability 70%-93.3%.⁴

Some studies now recommend core biopsy for suspicious-looking axillary lymph nodes to increase the predictability of metastatic lymph nodes.¹⁷ Gruber et al stressed the importance of ultrasound-guided core biopsy in patients who had equivocal FNA results.¹⁸

In our study, the overall accuracy of the preoperative AUS was 91.6%, and the sensitivity of AUS was 61.2%. Our results verify the importance of combined assessment for preoperative staging of the axilla. Consequently, we have introduced new protocols in our unit, including performing regular core biopsy of all lymph nodes when FNA is equivocal or insufficient.

CONCLUSION

Combined triple assessment increases the sensitivity, negative predictive value, and overall accuracy of preoperative staging of the axilla. The use of core biopsy helps when FNA result is equivocal or insufficient.