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Melanoma in children more likely to be invasive

Children under 10 more likely to have metastases in lymph nodes

Louise Prime

Thursday, 06 October 2011

Children aged under 10 years who have malignant melanoma appear to be more at risk of invasive disease than adults with the cancer, found research published early online in the journal Cancer.

Researchers from Johns Hopkins Children’s Center in the US investigated associations between lymph node biopsy results, tumour size and appearance, and age of people with malignant melanoma. Their study included 717 children and 1368 young adults, aged 20-24 years.

Overall, metastases were more likely to be found at sentinel lymph node biopsy in children (25% of cases) than in adults (14% of cases).

As expected, in both children and adults, melanoma thickness was the strongest predictor of lymph node metastases; but even allowing for tumour thickness, children had much higher risk of metastases than adults. Children with melanomas of 1.01-2mm thickness were six times as likely to have metastases found on sentinel lymph node biopsy as adults with similar thickness melanomas.

Younger children, under 10 years old, were also more likely than older children and young adults to have distant metastases and thicker tumours.

Patients’ age did not have a significant impact on survival rates from metastatic melanoma.

Current guidelines advise that lymph node removal should be undertaken in all patients with bleeding or irritated melanomas, or melanomas that are 1mm or more thick, which would indicate that they could have penetrated the skin deeply and metastasised. But the researchers say their results indicate that there could be “profound biological differences between childhood and adult melanoma”.

The researchers said: “Our finding is a powerful reminder that there’s much about paediatric melanoma that we don’t understand and that, just as is the case with other diseases, children are not small adults, but differ markedly in their response to disease.”

They add that because only 4% of malignant melanoma cases occur in children, their diagnosis and treatment can be dangerously delayed.

Both melanoma and non-melanoma skin cancer are becoming increasingly common in children, because of their greater exposure to the sun without protection and to indoor tanning.

The lead paediatric dermatologist from Johns Hopkins, who did not take part in this study, warned: “I advise parents to use sun screen religiously on infants and children during outdoor activities year round.”

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