Treatment implications of a positive sentinel lymph node biopsy for patients with early-stage breast carcinoma

BACKGROUND. Sentinel lymph node (SLN) mapping and biopsy is emerging as an alternative to axillary lymph node dissection (ALND) in determining the lym ph node status of patients with early-stage breast carcinoma. The hypothesi s of the technique is that the SLN is the first lymph node in the regional lymphatic basin that drains the primary tumor. Non-SLN (NSLN) metastasis in the axilla is unlikely if the axillary SLN shows no tumor involvement, and , thus, further axillary interference may be avoided. However, the optimal treatment of the axilla in which an SLN metastasis is found requires ongoin g evaluation. The objectives of this study were to evaluate the predictors for NSLN metastasis in the presence of a tumor-involved axillary SLN and to examine the treatment implications for patients with early-stage breast ca rcinoma. METHODS. Between June 1998 and May 2000, 167 patients participated in the p ilot study of SLN mapping and biopsy at Westmead Hospital. SLNs were identi fied successfully and biopsied in 140 axillae. All study patients also unde rwent ALND. The incidence of NSLN metastasis in the 51 patients with a SLN metastasis was correlated with clinical and pathologic characteristics. RESULTS. Of 51 patients with a positive SLN, 24 patients (47%) had NSLN met astases. The primary tumor size was the only significant predictor for NSLN involvement. NSLN metastasis occurred in 25% of patients (95% confidence i nterval [95%CI], 10-47%) with a primary tumor size less than or equal to 20 mm and in 67% of patients (95%CI, 46-83%) with a primary tumor size > 20 m m (P = 0.005). The size of the SLN metastasis was not associated significan tly with NSLN involvement. Three of 7 patients (43%) with an SLN micrometas tasis (< 1 mm) had NSLN involvement compared with 38 of 44 patients (48%) w ith an SLN macrometastasis (greater than or equal to 1 mm). CONCLUSIONS. The current study did not identify a subgroup of SLN positive patients in whom the incidence of NSLN involvement was low enough to warran t no further axillary interference. At present, a full axillary dissection should be performed in patients with a positive SLN. (C) 2001 American Canc er Society.