Cancer Cells in Sentinel Node Indicate Melanoma Risk

The prognosis of melanoma patients depends on the number of disseminated cancer cells per million lymphocytes in the sentinel node. Even very low numbers were found to be predictive for reduced survival. Anja Ulmer, Christoph Klein, and colleagues from the Universities of Tübingen (Germany) and Regensburg (Germany) studied 1,834 sentinel lymph nodes from 1,027 patients with melanoma and followed them for five years.

The scientists labeled disseminated cancer cells (DCCs) in the lymph nodes with a marker for melanoma cells, counted them, and calculated DCC density. They determined whether DCC density was related to a patient's survival and found that patients with high DCC density in the lymph nodes were more likely to die from melanoma within 5 years. A 10-fold increase in DCC density nearly doubled the risk of death.

A model was created based on tumor thickness, tumor ulceration, and lymph-node DCC density that provided survival prediction superior to that of a model based on the current standard staging recommendations. The investigators demonstrated that their new model predicted patients' prognosis more accurately. It classified 13% of patients in this cohort correctly as high risk for progression, which the standard model did not. This group of patients could potentially have benefitted from more aggressive treatments. The new model also correctly identified a group of low risk patients who had excellent long-term outcomes, whereas the standard model overestimated their risk of death.

The study was published in the February 2014 edition of PLoS Medicine. However, the results need to be validated in an independent study, in order to establish how this methodology could be used in a clinical setting. The authors said, "Our study shows that the extent of metastatic dissemination largely determines the disease courses of patients. The better we are able to predict the risk of patients to die from melanoma the better can we balance cost and benefit of potentially toxic therapies. For early melanoma, this might become even more important as novel drugs to prevent lethal metastasis are currently under investigation."

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University of Tübingen
University of Regensburg