Influence of Isolated Tumor Cells in Sentinel Nodes on Outcome in Small, Node-Negative (pT1N0M0) Breast Cancer

To evaluate the prognostic significance of isolated tumor cells found on sentinel node biopsy. The study is based on a prospectively followed up cohort of 1,865 consecutive patients diagnosed with pT1 (tumor size a parts per thousand currency sign20 mm) breast cancer in one university breast unit between February 2001 and August 2005. Of the 1,390 patients who received no neoadjuvant therapy and who underwent sentinel node biopsy, 63 had isolated tumor cells in the sentinel nodes (stage pT1N0i + M0, verified by axillary node dissection) and 868 did not (pT1N0i - M0). Median follow-up time was 55 months. Patients with pN0i+ disease received systemic adjuvant therapies more often than those with pN0i- disease (87 versus 51%; P < 0.0001). There was no significant difference between the groups in terms of 5-year recurrence-free survival (90.3 versus 93.2%, respectively; P = 0.32) or overall survival, but patients with pN0i+ cancer had less favorable 5-year breast-cancer-specific survival (95.2 versus 98.4%; P = 0.035) than those with pN0i- cancer, and they were more frequently diagnosed with distant metastases from breast cancer during the first 5 years of follow-up (8.1 versus 1.9%, respectively; P = 0.001). Some conventional prognostic factors, such as histological grade, steroid hormone receptor status, and cell proliferation rate, were more strongly associated with outcome than was pN0i status. The findings suggest that presence of isolated tumor cells in the sentinel nodes is an adverse prognostic factor in early breast cancer, but its prognostic significance in association with standard factors may be limited.