Melanoma: Signs and Subtypes

For decades, the genetic basis of pediatric melanoma was a mystery. But St. Jude scientists recently discovered the molecular signatures of three pediatric melanoma subtypes.

Pediatric melanoma survivor and aspiring sign language interpreter Summer Bate teaches sign language to her oncologist, Alberto Pappo, MD, during a recent checkup.

Pediatric melanoma survivor and aspiring sign language interpreter Summer Bate teaches sign language to her oncologist, Alberto Pappo, MD, during a recent checkup. 

It was supposed to be a routine physical—nothing out of the ordinary. But that all changed when Summer Bate’s family physician discovered something unusual: a large mole on her upper back.

The eighth-grader had known about the mole for years, but had never given it a second thought. Summer’s physician encouraged her to visit a dermatologist as soon as possible. Summer’s mother, Kristy Harvey, scheduled the appointment. But when Summer got the chance to travel to Colorado, the appointment was cancelled.

Neither Summer nor her mom thought of the mole again until several years later, when the teen noticed that a white ring had developed around the spot. Nearly four years after the original appointment had been cancelled, she finally visited a dermatologist.

A biopsy revealed melanoma, the most dangerous type of skin cancer. Summer was only 17 years old.

“It was a complete shock,” Kristy says. “Summer always used sunscreen and was the first person in our family to ever be diagnosed with melanoma.”

More than 9 out of 10 young patients with conventional melanoma had DNA changes caused by sun damage. St. Jude scientists emphasize that sun protection must start early and should be a lifelong habit.

 

Melanoma on the rise

Pediatric melanoma is quite rare, even for blonde girls with pale skin like Summer.

In fact, on average, only 400 people in the U.S. aged 19 or younger are found to have melanoma each year, according to the National Cancer Institute. Unfortunately, this incidence rate has risen steadily in recent decades, by upwards of 2 percent annually, primarily in those ages 15 to 19.

To better understand pediatric melanoma and improve treatment, Alberto Pappo, MD, and Armita Bahrami, MD, of St. Jude Oncology, led research to improve understanding and treatment of the three most common subtypes. The effort was part of the  St. Jude Children’s Research Hospital – Washington University Pediatric Cancer Genome Project, which used next-generation, whole genome sequencing to determine the molecular signatures of pediatric melanoma for the first time.

Banning the rays

Scientists studied 23 melanoma patients, who were between 9 months and 19 years old. The investigators focused on a pediatric melanoma subtype that is identical to adult melanomas when viewed under the microscope. They also examined a subtype that arises in large moles present at birth, as well as a spitzoid melanoma subtype, which is often difficult to diagnose.

“We found that conventional melanoma is essentially the same disease in children and adults, with DNA changes caused by sun damage,” Pappo says. “Most of those patients carry a mutation of the BRAF gene, which is similar to the melanoma of many adult patients.”

He says these findings further emphasize the importance of adopting sun protection habits at a young age.

The team also noticed that children and teens who were born with large moles had a mutation in a gene known as NRAS.

“Although this type of melanoma is rarer, it is usually very aggressive and difficult to treat,” Pappo explains. “But treatment options may improve, since we have now targeted a gene mutation that each of those patients had.”

Pappo and Armita Bahrami, MD, of St. Jude Oncology, discuss their recent discoveries, which shed new light on melanoma’s three most common subtypes. 

 
 

Predicting spitzoids

In the meantime, the behavior of the most common subtype of pediatric melanoma, spitzoid, is especially challenging to predict.

“Childhood spitzoids are typically not as aggressive as conventional melanomas, so perhaps they should not be treated as aggressively as conventional melanomas are,” Bahrami observes. “Still, some of them have an unpredictable course and can be aggressive.”

Bahrami identified a genetic marker known as a TERT promoter mutation. This discovery may help scientists pinpoint children who have the aggressive type of spitzoid that requires more intensive therapy.

The recent St. Jude findings make Pappo optimistic that young melanoma patients will be included in the pipeline of new drugs much earlier than they are currently.

“We need to make it easier for young people to try promising treatments that are being studied in adults,” he says. “Clinical trials should start including younger patients who have conventional melanoma as well, since our study has demonstrated these patients share many genomic similarities, when compared to adult patients.”

Made in the shade

Summer says her experiences with pediatric melanoma have ultimately been positive. Her tumor was surgically removed at St. Jude more than three years ago. She also received interferon therapy for 36 weeks. Then a new melanoma lesion developed, which was surgically removed.

Summer’s disease has been in remission since August of 2012.

She completed her final semester of high school through the St. Jude School Program. Currently, she is in college, pursuing her goal of becoming a sign language interpreter.

“My experiences at St. Jude have definitely changed my life,” Summer says. “I have learned to not take anything for granted. You never know what can happen, so you need to live every day the best you can and stay as positive as possible.” 

Reprinted from Promise, Summer 2015

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