The Relevance of Ultrasound Imaging of Suspicious Axillary Lymph Nodes and Fine-needle Aspiration Biopsy in the Post-ACOSOG Z11 Era in Early Breast Cancer

Abstract

Rationale and objectives: Evaluation of nodal involvement in early-stage breast cancers (T1 or T2) changed following the Z11 trial; however, not all patients meet the Z11 inclusion criteria. Hence, the relevance of ultrasound imaging of the axilla and fine-needle aspiration biopsy (FNA) in early-stage breast cancers was investigated.

Materials and methods: In this single-center, retrospective study, 758 subjects had pathology-verified breast cancer diagnosis over a 3-year period, of which 128 subjects with T1 or T2 breast tumors had abnormal axillary lymph nodes on ultrasound, had FNA, and proceeded to axillary surgery. Ultrasound images were reviewed and analyzed using multivariable logistic regression to identify the features predictive of positive FNA. Accuracy of FNA was quantified as the area under the receiver operating characteristic curve with axillary surgery as reference standard.

Results: Of 128 subjects, 61 were positive on FNA and 65 were positive on axillary surgery. Sensitivity, specificity, positive predictive value, and negative predictive value of FNA were 52 of 65 (80%), 54 of 63 (85.7%), 52 of 61(85.2%), and 54 of 67 (80.5%), respectively. After adjusting for neoadjuvant chemotherapy between FNA and surgery, a positive FNA was associated with higher likelihood for positive axillary surgery (odds ratio: 22.7; 95% confidence interval [CI]: 7.2-71.3, P < .0001), and the accuracy of FNA was 0.801 (95% CI: 0.727-0.876). Among ultrasound imaging features, cortical thickness and abnormal hilum were predictive (P < .017) of positive FNA with accuracy of 0.817 (95% CI: 0.741-0.893).

Conclusions: Ultrasound imaging and FNA can play an important role in the management of early breast cancers even in the post-Z11 era. Higher weightage can be accorded to cortical thickness and hilum during ultrasound evaluation.

Keywords: Breast cancer; axilla; axillary lymph node dissection; fine-needle aspiration; lymph node; sentinel node biopsy; ultrasound.

Figure 1

ROC curve indicating that cortical thickness in mm and hilum status were predictive of a positive result from ultrasound-guided FNA.

Figure 2

ROC curves showing that a positive FNAB is predictive of axillary lymph node metastasis from surgical procedure (a) for the cohort of subjects who did not undergo interim NCT, and (b) for the entire study sample that included subjects who underwent NCT.

Figure 3

48 year old female with a lower inner quadrant invasive ductal carcinoma (T2 tumor–2.1 × 1.6 cm mass, grade-3) (top row). Right axilla (RMLO view) demonstrates an oval heterogeneous anechoic lymph node (left bottom), without fatty hila, cortical thickening and abnormal vascularity (image not shown). FNA (needle in appropriate position, bottom right) was positive.

Figure 4

75 year old female, with a left breast primary tumor (T1 – 1.4 × 1 cm at 12:00 clock) that was pathology-verified as invasive ductal carcinoma. Evaluation of the axilla demonstrated a round LN, with eccentric displacement of central fatty hila, focal cortical thickness of 5mm and non-hilar blood flow. FNA was positive for malignant cells of ductal origin.

Figure 5

31 year old female presenting with a palpable right axillary mass. Baseline mammogram was negative (not shown). US evaluation of the right axilla demonstrated an enlarged lymph node with eccentric displacement of fatty hila, diffuse cortical thickness exceeding 3mm and non-hilar abnormal blood flow on color imaging (left and middle). FNA showing the needle in the abnormal cortex (right). Histology: Focal necrosis and inflammation, no evidence of malignancy (Kikuchi disease was a suggested possibility). Distinction between a reactive, inflamed node from any cause and metastatic disease is difficult on imaging.