Impact of Micrometastases in the Sentinel Node of Patients With Invasive Breast Cancer

Abstract

Lymph node metastases are the most significant prognostic indicator for patients with breast cancer. Sentinel node biopsy (SNB) has led to an increase in the detection of micrometastases in the sentinel node (SN). This prospective study was designed to determine the survival impact of micrometastases in SNs of patients with invasive breast cancer. This study is based on the new sixth edition of the American Joint Committee on Cancer (AJCC) staging criteria. Between January 1, 1992 and April 30, 1999, 790 patients entered this prospective study at the John Wayne Cancer Institute. The SN was examined first by hematoxylin and eosin (HE), and if the SN was negative with HE, then immunohistochemical staining was performed. The patients were then divided into four groups based on AJCC nodal staging: pN0(i-), no evidence of tumor (n = 486); pN0(i+), tumor deposit < or = 0.2 mm (n = 84); pN1mi, tumor deposit more than 0.2 mm but < or = 2 mm (n = 54), and pN1, tumor deposit more than 2 mm (n = 166). Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The log-rank test was used to determine differences in DFS and OS of patients from different groups. At a median follow-up of 72.5 months, the size of SN metastases was a significant predictor of DFS and OS. Patients with micrometastatic tumor deposits, pN0(i+) or pN1mi, do not seem to have a worse 8-year DFS or OS compared with SN-negative patients. As expected, there was a significant decrease in 8-year DFS and OS in patients with pN1 disease in the SN.