Predictive factors for metastatic involvement of nonsentinel nodes in patients with breast cancer.

Background: The potential morbidity of an axillary lymph node dissection in patients with breast cancer can be avoided in patients with a negative sentinel node (SN).

Hypothesis: It may be possible to identify a subset of patients with a positive SN and without metastases in the remaining axillary lymph nodes.

Design: Case-control study.

Setting: Both primary and referral hospital care.

Patients: Data were studied for 255 consecutive patients with stage T1 or T2 breast cancer who had a successful identification of the SN.

Interventions: In patients with a positive SN, histological examination of all non-SNs that were negative by routine examination was the same as that for SNs (multiple sectioning and immunohistochemical analysis).

Main Outcome Measures: The incidence of non-SN metastases was correlated with the surface area and number of SN metastases and primary tumor characteristics. A micrometastasis was defined as less than 1 mm(2).

Results: Of 255 patients, the SN appeared to be positive in 93 (36%). Subsequent axillary lymph node dissection revealed positive non-SNs in 46 patients (49%). Patients with a single positive SN and patients with metastases less than 1 mm(2) in the SN had significantly less non-SN involvement than patients with more than 1 positive SN (40% vs. 78%) and patients with macrometastases (27% vs. 49%).

Conclusions: The incidence of non-SN metastases seemed to be related to the number of positive SNs and the size of SN metastases. However, in the group of patients with a positive SN, it was not possible to identify a subset of patients without non-SN metastases.