Breast cancer survival in relation to the metastatic tumor burden in axillary lymph nodes

The aim of this study was to determine the prognostic significance of lymph node micrometastases in patients with breast cancer.

Between September 2000 and January 2004, 3,369 patients with breast cancer were included in a prospective cohort. According to their lymph node status, they were classified in the following four groups: 2,383 were node negative, 107 had isolated tumor cells, 123 had micrometastases, and 756 had macrometastases. Median follow-up time was 52 months. Kaplan-Meier estimates and the multivariate Cox proportional hazard regression model were used to analyze survival.

Five-year cause-specific and event-free survival rates were lower for patients with micrometastases (pN1mi) than for node-negative (pN0) patients (94.1% v 96.9% and 79.6% v 87.1%, respectively; P = .020 and P = .032, respectively). There was no significant survival difference between node-negative patients and those with isolated tumor cells. The overall survival of pN1mi and pN0 patients did not differ.

This study demonstrates a worse prognosis for patients with micrometastases than for node-negative patients.