T1 breast cancer: identification of patients at low risk of axillary lymph node metastases.

Objective: The status of the axillary lymph nodes is one of the most important prognostic factors in patients with breast cancer. A panel of molecular markers of tumor aggressiveness in addition to conventional clinical and histopathologic features were analyzed in an attempt to identify a subgroup of patients with a low risk of axillary lymph node metastases.

Material And Methods: Data from 358 patients with T1 breast cancer who underwent level I/II axillary lymph node dissection (ALND) were investigated. Hormone receptor status, Ki-67, S-phase fraction, DNA ploidy, HER-2/neu, p53, epidermal growth factor receptor, urokinase type plasminogen activator, plasminogen activator inhibitor-1, bone marrow micrometastases as well as patient age, menopausal status, tumor site, tumor size, histologic type, tumor grade, carcinoma in situ, multifocality, and lymph vascular invasion (LVI) were studied to predict axillary lymph node status.

Results: In a multivariate logistic regression analysis LVI (present v.s. not present), Ki-67 (> or = 18% v.s. < 18%), tumor size (1.1-2 cm v.s. < or = 1 cm), and histologic grade (G3 v.s. G1/2) were identified as independent predictive factors of axillary lymph node metastases. Approximately 13% of patients (n = 47) with well or moderately differentiated tumors less than or equal to 1 cm, no lymph vascular invasion, and a low Ki-67 staining were identified as having a low risk of axillary lymph node metastases of 4.3%. However, 20 patients with all four unfavorable predictive factors had a 75% incidence of axillary lymph node involvement.

Conclusion: Primary tumor characteristics can be used to identify a subgroup of patients with a low risk of axillary lymph node metastases in T1 breast cancer. Preoperative risk assessment might be used to omit routine ALND in those patients at low risk of axillary lymph node metastases.