Role of sonography in the diagnosis of axillary lymph node metastases in breast cancer: a systematic review.
OBJECTIVE: The purpose of our study was to evaluate the accuracy of sonography and sonographically guided biopsy in the preoperative diagnosis of metastatic invasion of the axilla in patients with breast carcinoma. MATERIALS AND METHODS: We performed a MEDLINE search (keywords, "sonography" OR "ultrasound" AND "axillary") and a manual search of the references of relevant studies and reviews of preoperative diagnosis on sonography of possible axillary metastases. The gold standard required was axillary lymph node dissection; we accepted sentinel node biopsy as an alternative gold standard. Considering the sonographic findings and the results of the sonographically guided biopsy, the sensitivity and specificity were calculated using metaanalysis. We also checked the existence of heterogeneity of the summary results. RESULTS: Sixteen articles were selected. In sonography of axillae without palpable nodes, and using lymph node size as the criterion for positivity, sensitivity varied between 48.8% (95% confidence interval, 39.6-58%) and 87.1% (76.1-94.3%) and specificity, between 55.6% (44.7-66.3%) and 97.3% (86.1-99.9%). When lymph node morphology was used as the criterion for positivity, sensitivity ranged from 26.4% (15.3-40.3%) to 75.9% (56.4-89.7%) and specificity, from 88.4% (82.1-93.1%) to 98.1% (90.1-99.9%). The results are different if axillae with palpable nodes are included. The sonographically guided biopsy shows a sensitivity that varies between 30.6% (22.5-39.6%) and 62.9% (49.7-74.8%) and a specificity of 100% (94.8-100%). Many of the summary results obtained after meta-analysis show a heterogeneity that disappears, on occasion, on excluding the studies that use a double gold standard. CONCLUSION: Axillary sonography is moderately sensitive and fairly specific in the diagnosis of axillary metastatic involvement. Sonographically guided biopsy of the sonographically suspicious nodes somewhat increases the specificity, which reaches 100%. Negative sonographic results do not exclude axillary lymph node metastases.