Background: In melanoma, a direct relationship exists between the number of nodes involved with metastatic disease and prognosis. This study was undertaken to determine whether an individual with metastatic disease confined to the sentinel lymph nodes (SLNs) would have a better prognosis than individuals with metastatic disease that has spread to the non-SLNs, regardless of the number of nodes involved.
Methods: The study group consists of 229 melanoma patients with a positive SLN who underwent regional nodal dissection. Cox proportional hazard regression models were used to assess association of the number of SLNs and non-SLNs involved with disease with overall survival (OS) and disease-free survival (DFS).
Results: DFS and OS were unchanged regardless of how many SLNs were positive, as long as all disease was confined to SLNs. Among 183 patients without involvement of non-SLNs, OS remained the same despite an increasing number of SLNs involved (P = .59). This was true after controlling for ulceration, Breslow depth, age, sex, and adjuvant treatment. Once disease was present beyond the SLN, DFS and OS were negatively affected. Among patients with involvement of non-SLNs, there was no statistically significant association between the number of positive SLNs and survival. The risk of mortality increased with the number of non-SLNs involved with metastatic disease (P < .001).
Conclusions: The number of regional nodes involved with metastatic disease does not affect DFS and OS if disease is confined to the SLNs. Consideration should be given to specifying SLN versus non-SLN involvement in the American Joint Committee on Cancer staging manual.