Metastatic Tumor Volume and Extranodal Tumor Extension: Clinical Significance in Patients With Stage II Breast Cancer

Abstract

Context Lymph node status and the number of lymph node (LN) positive for cancer cells are the most important prognostic factors in breast cancer. Extranodal tumor extension (ENTE) has been used as a histopathologic feature to classify patients into high risk versus low risk for local recurrence. However, in the current era of early detection and systemic therapy, the prognostic significance of ENTE is not as well defined in patients with 1 to 3 LNs positive for cancer. Objective To determine whether the amount of tumor burden in an axillary dissection or the presence of ENTE provides any additional information regarding patient outcome in patents with 1 to 3 positive LN results. Design Clinical and pathologic factors were identified for 456 patients with breast cancer at the University of Texas MD Anderson Cancer Center, Houston, who had pT1 tumors and 1 to 3 LNs positive for cancer and were treated by mastectomy, with or without postmastectomy radiotherapy, between 1978 and 2007. Results Of the 456 patients, 257 (56.4%), 141 (31.6%), and 58 (12.7%) patients had 1, 2, or 3 positive LN results, respectively. Extranodal tumor extension was present in 99 patients (21.7%) and was absent in the remaining 357 cases (78.3%). Seventy-six patients (16.7%) received radiation therapy. Patients had both worse overall survival time and disease-free survival when ENTE was present, regardless of the amount, as long as the treatment era was not included in the multivariate analysis (pre-2000 versus post-2000). However, ENTE was no longer significant on multivariate analysis when the year of treatment was taken into account. Conclusions The number of positive LNs remains an important predictor of survival in patients with 1 to 3 positive LN results, but the prognostic significance of ENTE in this cohort of patients has diminished over time.