Some Patients with Positive Sentinel Nodes May Not Need Axillary Dissection

December 17, 2007

Some breast cancer patients with positive sentinel lymph nodes have factors associated with a low probability of having any other positive nodes and may therefore be able to safely skip completion axillary dissection, new data show.

Some breast cancer patients with positive sentinel lymph nodes have factors associated with a low probability of having any other positive nodes and may therefore be able to safely skip completion axillary dissection, new data show.

Thomas B. Julian, MD
Photo Courtesy SABCS/Todd Buchanan 2007

In a study presented at this year's SABCS (abstract 51), Thomas B. Julian, MD, and colleagues with the National Surgical Adjuvant Breast and Bowel Project analyzed data from the NSABP B-32 randomized trial. In that trial, women with breast cancer and clinically negative axillary nodes underwent sentinel node resection (using a combination of isotope, dye, and palpation) always followed by axillary dissection (Group 1) or followed by axillary dissection only when the sentinel node was positive, as determined by hematoxylin and eosin staining (H&E) (Group 2). Analyses were based on the 1166 patients overall who had a positive sentinel node, underwent axillary dissection, and had complete data. In univariate analysis, the factors associated with a higher rate of positive non-sentinel nodes were study group (Group 2), fewer sentinel nodes examined, fewer hot spots, more positive sentinel nodes, larger clinical tumor size, primary tumor location in the upper outer quadrant, lymphovascular invasion, and HER2 positivity. In contrast, age, type of biopsy, histologic grade, and hormone-receptor status were not associated with this outcome. In a multivariate analysis among Group 1 patients, the odds of having positive non-sentinel nodes increased significantly with increasing number of positive sentinel nodes (odds ratio, 2.01), larger clinical tumor size (1.22), and the presence of lymphovascular invasion (1.88). Odds decreased significantly with increasing number of sentinel nodes examined (0.73) and increasing number of hot spots (0.56). Similarly, in a multivariate analysis among Group 2 patients, the odds of having positive non-sentinel nodes increased significantly with increasing number of positive sentinel nodes (odds ratio, 2.12), larger clinical tumor size (1.22), and the presence of lymphovascular invasion (1.88). Odds decreased significantly with increasing number of sentinel nodes examined (0.73) and increasing number of hot spots (0.56). Combinations of these factors identified subsets of patients who had a less than 20% probability of having positive non-sentinel lymph nodes. In particular, Group 2 patients who had one hot spot, no lymphovascular invasion, a single positive sentinel node, and five sentinel nodes examined had probabilities of roughly 5% to 15%, depending on clinical tumor size. "Although in the majority of patients identified in this modeling with positive sentinel nodes an axillary dissection is considered to be necessary, a completion axillary dissection may be avoided in selected subsets of patients where the combinations of low-probability variables exist," Dr. Julian said. "We feel that these would include patients who have very small tumors, no lymphovascular invasion, and only a single positive sentinel node out of multiple nodes, and it looks like by this modeling that that starts at a total of five nodes."

Disclosures:

The author(s) have no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.