Counting Cells in Breast Cancer Lymph Node Metastases.
Chad Luedtke, Lee Tan, Edi Brogi, Sujata Patil, Dilip Giri. Memorial Sloan-Kettering Cancer Center, New York, NY
Background: The 2010 AJCC staging of breast cancer axillary nodal metastases classifies isolated tumor cells (ITCs) as clusters of cells not greater than 0.2 mm or nonconfluent clusters not exceeding 200 cells in a single histologic lymph node cross section. Since counting cells adds a new dimension to ITC assessment, we examined the rate of upstage from pN0(i+) to pN1mi when cell counts are used.
Design: Lymph nodes were selected from a cohort of 83 patients initially node negative that converted to node positive following deeper levels with hematoxylin and eosin (HE) and cytokeratin (CK) stains. Each case was reassessed by a surgical breast pathologist using glass and digitally scanned slides. The pN stage was re-calculated for each patient using both the 2002 and 2010 AJCC staging guidelines.
Results: Using the 2002 AJCC classification, 43/83 cases were pN0(i+) because they had cluster sizes <0.2mm. 2 of these cases were upgraded from pN0(i+) to pN1mi using cell count according to the 2010 AJCC guidelines, giving a 5% (2/43) upstage rate. Both upgrades occurred using glass and digital slides with CK stain only. No upgrades occurred with HE. Additionally, the metastases in these cases were characterized by dispersed single cells and nearly confluent cell clusters and were associated with an ipsilateral invasive lobular carcinoma.
Conclusions: In this study, the upstage rate from pN0(i+) to pN1mi is 5% using the 2010 AJCC staging guidelines. The factors associated with upstaging are the stain, the type of metastases, and the histological subtype of the primary breast cancer. Cell counts should continue to be an important consideration of potential clinical significance.
Tuesday, March 1, 2011 2:15 PM
Platform Session: Section B, Tuesday Afternoon