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.