Background: It is unclear which breast cancer patients with positive sentinel lymph nodes (SLNs) require a completion axillary lymph node dissection. Our aim was to determine factors that predict involvement of nonsentinel axillary nodes (NSLNs) in patients with positive SLNs.
Methods: We reviewed the records of all patients with invasive breast cancer who underwent SLN biopsy at our institution between 1993 and August 2001. Multivariate analysis was used to identify clinicopathologic features in SLN-positive patients that predict involvement of NSLNs.
Results: A total of 131 patients had a positive SLN and underwent completion axillary lymph node dissection. Multivariate analysis revealed that primary tumor >2 cm (P =.009), SLN metastasis >2 mm (P =.024), and lymphovascular invasion (P =.028) were independent predictors of positive NSLNs. The number of SLNs harvested was a significant negative predictor (P =.04). In our model, based on the presence of these factors, the positive predictive value was 100% for a score of 4.
Conclusions: The likelihood of positive NSLNs correlates with primary tumor size, size of the largest SLN metastasis, and presence of lymphovascular invasion. A scoring system incorporating these factors may help determine which patients would benefit from additional axillary surgery.