Frequency of sentinel lymph node metastases in patients with favorable breast cancer histologic subtypes

Background The need for axillary nodal staging in favorable histologic subtypes of breast cancer is controversial. Methods Patients with clinical stage T1-2, N0 breast cancer were enrolled in a prospective, multi-institutional study. All patients underwent sentinel lymph node (SLN) biopsy followed by completion level I/II axillary dissection. Results SLN were identified in 3,106 of 3,324 patients (93%). Axillary metastases were found in 35% and 40% of patients with infiltrating ductal carcinoma and infiltrating lobular carcinoma, respectively. Among tumor subtypes, positive nodes were found in 17% of patients with pure tubular carcinoma, 7% of patients with papillary cancer, 6% of patients with colloid (mucinous) carcinoma, 21% of patients with medullary carcinoma, and 8% of patients with DCIS with microinvasion. Conclusions Patients with favorable breast cancer subtypes have a significant rate of axillary nodal metastasis. Axillary nodal staging remains important in such patients; SLN biopsy is an ideal method to obtain this staging information.