[209] Morphologic Features of Breast Carcinoma Are Associated with False Negative Screening by Axillary Ultrasound

TT Ha, S Charoenthammaraksa, C Liao, RA Schmidt, HA Sattar. University of Chicago, Chicago, IL

Background: Axillary ultrasound (AUS) and ultrasound-guided lymph node biopsy (LNB) are important breast cancer staging adjuncts, obviating the need for sentinel lymph node biopsy (SLNB) in many cases. Patients with normal findings on AUS/LNB still undergo SLNB to ensure adequate screening. Given the complexity of this screening algorithm, it is necessary to identify patient subsets that are less likely to benefit from AUS screening.
Design: 461 patients who underwent AUS screening (2004-2008) were stratified into 4 groups: true positive (TP), false positive (FP), true negative (TN), and false negative (FN) according to final nodal status determined by ultrasound-guided axillary node biopsy, follow-up SLNB or axillary dissection. Histology of resected primary breast lesions from a subset (236 consecutive cases; 2004-2006) of these patients was reviewed to determine whether lymphoplasmacytic infiltrate, tumor necrosis, micropapillary features or lobular-like growth pattern were associated with failure of AUS screening.
Results: In total, 135 patients were node positive and 326 were node negative. AUS/LNB accurately predicted final nodal status in 75% of cases (348/461; sensitivity 0.50, specificity 0.86, PPV 0.60, NPV 0.81). Micropapillary features were present in 38 cases (range: 5% to 100% of tumor volume) and were more prevalent in FN cases than in TN cases (26.3% vs. 12.7%; p = 0.047). Lobular-like growth pattern was identified in 55 cases (range:10-100% of tumor volume) and was more prevalent in FN cases, compared to TN cases (39.5% vs. 22.5%; p = 0.04). Lymphoplasmacytic infiltrate and tumor necrosis did not vary significantly between the four examined groups.
Conclusions: As a screening method, AUS/LNB has relatively low sensitivity. Identifing factors that contribute to the high FN rate may improve this method's sensitivity. This study identifies micropapillary features and lobular-like growth pattern as two morphologic characteristics of the index breast carcinoma that are more likely associated with FN screening. Patients whose primary lesion exhibits these features on biopsy may benefit from proceeding directly to SLNB in order to eliminate the costs of unnecessary procedures. Larger studies are warrented to further validate these results.
Category: Breast

Monday, March 22, 2010 1:00 PM

Poster Session II # 28, Monday Afternoon

 

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