Predicting the spread of a melanoma to other parts of the body

Linked Article:   El Sharouni et al. Br J Dermatol 2021; 185 :412–418. Melanoma is a serious form of skin cancer that arises when pigment cells in the skin become malignant (cancerous). During their lifetime melanoma develops in about 1 in 40 people in the UK and 1 in 20 people in Australia. Melanoma can spread to other parts of the body (i.e. ‘metastasize’), and when this occurs the person’s life is at serious risk. In most cases, melanoma cells spread first in lymph vessels (that drain tissue fluid) to lymph nodes (glands). The first lymph node that the melanoma cells encounter is called the ‘sentinel’ node. In this study, using information from the Netherlands and Australia, we aimed to find out if an Australian model that was developed to predict whether melanoma cells are likely to be present in a sentinel node also applied to a European population from the Netherlands. We did this by checking whether the predictions that were calculated for Australian patients could be applied directly to Dutch patients, a process known as ‘external validation’. We found that the Australian model worked well in Dutch patients. This means that the model developed in Australia can also be used in other countries to predict the chance that melanoma cells will be present in a sentinel node (i.e. a ‘positive’ sentinel node). This can spare patients with a low risk of having a positive sentinel node the inconvenience, cost and potential risks of this procedure, while at the same time identifying patients who are at high risk of having a positive sentinel node.