Melanoma May Be More Aggressive in Kids

Some children with melanoma are more likely to have invasive disease than adults with this potentially deadly type of skin cancer, a new study indicates.

The findings suggest that there may be biological differences between childhood and adult melanoma, said the researchers at the Johns Hopkins Children's Center in Baltimore.

They analyzed the medical records of 717 children and 1,368 young adults (aged 20 to 24) diagnosed with melanoma and compared sentinel lymph node biopsy results based on tumor size, tumor appearance and patient age. Sentinel lymph nodes are those that surround the tumor, and sentinel lymph node biopsy is the standard way to assess spread (metastasis) of the cancer and determine treatment.

Cancer cells were found in the sentinel lymph nodes of 25 percent of children and 14 percent of adults who had biopsies. Tumor thickness was the strongest predictor of lymph node metastases in both children and adults.

But children with tumors with a thickness of 1.01 and 2 millimeters were nearly six times more likely than young adults with same-thickness tumors to have cancer cells in sentinel lymph nodes.

The researchers also found that children younger than 10 were more likely to have distant metastases (spread of cancer beyond the immediate tumor site) and greater tumor thickness, compared with older children and young adults.

Regardless of age, patients with bleeding tumors or those with open sores were more likely to have metastases.

The study was published online Oct. 5 in the journal Cancer.

"Our finding is a powerful reminder that there's much about pediatric 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," senior investigator Dr. John Strouse, a pediatric hematologist and oncologist, said in a Johns Hopkins Medicine news release.

Although still uncommon, melanoma diagnoses in children are increasing, and unprotected sun exposure, sunburns and indoor tanning are some of the known causes.