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 sen tinel node (SN). Hypothesis: It may be possible to identify a subset of patients with a posi tive 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 T 2 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 wi th the surface area and number of SN metastases and primary tumor character istics. A micrometastasis was defined as less than 1 mm(2). Results: Of 255 patients, the SN appeared to be positive in 93 (36%). Subse quent axillary lymph node dissection revealed positive non-SNs in 46 patien ts (49%). Patients with a single positive SN and patients with metastases l ess than 1 mm(2) in the SN had significantly less non-SN involvement than p atients with more than 1 positive SN (40% vs 78%) and patients with macrome tastases (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 grou p of patients with a positive SN, it was not possible to identify a subset of patients without non-SN metastases.