CHICAGO – Extracapsular extension, or extracapsular spread (ECS), has been recognized as a risk factor in melanoma patients with macrometastatic (N+) disease, but a study from the United Kingdom has found it may also be an important indicator of progression-free and overall survival in patients who have sentinel node positive (SLN+) micrometastatic disease, a researcher reported at the.
“There is limited published data on ECS in micrometastatic disease, although there is progression-free survival data published in the literature,” Michelle Lo, MBCHB, MRCS, of Norfolk and Norwich University Hospitals, in Norwich, England, said in presenting the results. “The goal of the study was to determine the incidence of ECS in the micrometastatic group and to determine the prognostic significance of this.”
The study found that the incidence of ECS in the N+ group was significantly higher than the SLN+ group, 52.4% vs. 16.2% (P less than .0001). ECS proved to be a significant prognostic indicator of disease-specific survival and overall survival for both N+ and SLN+ disease. “There was no statistical difference in Breslow thickness between the two groups regardless of ECS,” she said.
Both the N+ and SLN+ groups with ECS had more lymph nodes than the ECS-absent subgroups, Dr. Lo said. However, in the ECS-absent subgroups, N+ patients had twice the number of lymph nodes than SLN+ patients. “This would suggest that ECS is a high-risk phenotype from the outset of metastases rather than something that’s developed over time,” she said. “Our data is in line with international staging data.”