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June 8, 2005

BehindTheMedspeak: Melanoma in children on the rise

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It's still rare: last year 50,000 cases of melanoma were diagnosed in the U.S., yet only 400 occurred in people under 20.

That's fewer than 1% of all cases.

Yet that number represents a marked increase over decades previous: "Since 1978 the rate of melanoma in the young has increased by 1.3% a year, according to the National Cancer Institute," wrote Christina S. N. Lewis in an eye–opening story that appeared in yesterday's Wall Street Journal.

Melanoma in young children is not believed to be related to UV radiation but, rather, to be the result of a genetic predisposition.

Now, it seems to me that there is a huge potential payoff here in terms of understanding the trigger that causes a melanoma to begin.

If this small group of children diagnosed each year with melanoma share a hardwired genetic predisposition to the disease, wouldn't an all–out effort at sequencing their genomes quite possibly lead to a common genetic locus being identified as associated with melanoma?

If such a genetic sequence were to be identified it could lead to predictive diagnosis in those especially at risk, either because of a family history or a weakened immune system.

As Willie Sutton replied, when asked why he robbed banks, "Because that's where the money is."

One relatively new development not noted in the Journal story is the use of sequential whole body photography and subsequent computer analysis of changes in moles over time.

Dermatologists adapted this technique from astronomers who use computers to flag infinitesimal changes in vast fields of stars.

The standard mnemonic for melanoma surveillance is ABCD:

A = Asymmetry:
A_28


B = Borders (irregular):
B_40


C = Color (various):
C_37


D = Diameter (larger than a pencil):
D_20


Here's the Journal story.

    Melanoma in Children Is Rare But Number of Cases Increases, Cause Remains Unknown;

    Sun exposure may not be the reason, say doctors

    In the summer of 2002, Mark and Mylissa Horrocks, both 27 years old, of Cape Coral, Fla., noticed a small bump on their toddler's left knee.

    It was flesh-colored and bled when Bella bumped it.

    A few months later they pointed it out to their pediatrician, who prescribed a wart-removing acid that they dutifully applied to Bella's knee daily.

    But after nearly a year, the bump was still there, so despite their doctor's reassurances, the Horrocks took Bella to a dermatologist.

    The specialist removed the growth within a half hour of seeing her.

    Relieved, the family left for a two-week vacation to visit relatives in upstate New York.

    When they returned home, they realized the dermatologist had left several urgent messages.

    Bella had advanced melanoma, the rarest and deadliest form of skin cancer that until recently was unknown in young children.

    "No one thinks melanoma occurs in kids," says Casey Culbertson, head of the Melanoma Research Foundation.

    Melanoma in young children is extremely rare.

    Of the approximately 50,000 cases of melanoma diagnosed each year in the U.S., only about 400 involve people under 20, according to the National Cancer Institute.

    But the number of affected children is growing.

    Since 1978, the rate of melanoma in the young has increased by 1.3% a year, according to the National Cancer Institute.

    The causes of pediatric melanoma are a mystery to doctors.

    Although the link between sun and skin cancer is well established in dermatology, some doctors think melanoma in children isn't directly caused by the sun.

    John DiGiovanna, a Brown Medical School dermatologist, says that young children can't have been exposed to enough ultraviolet radiation to cause cancer.

    "It has to be a genetic predisposition because it's clearly not sun-related," Dr. DiGiovanna says.

    By contrast, UV radiation is strongly linked with higher melanoma incidence in adults.

    The increase in incidence rates for melanoma in children may be caused by better surveillance and awareness among parents, Dr. DiGiovanna speculates, noting that skin cancer in adults has received significant media coverage.

    The risk factors for children and adults are similar.

    Children with many moles, particularly moles present from birth or of unusual size, are at higher risk.

    Those with a family history of melanoma are at greater risk, as are people whose immune system has been weakened, Dr. DiGiovanna says.

    Children do face some unique risks, such as maternal transmission of the cancer while in utero.

    Also, doctors say cancers in children often go undiagnosed for longer because doctors don't think to look for skin cancer in youngsters.

    After a month of calling different medical centers, Mark Horrocks was eventually referred to St. Jude Children's Research Hospital in Memphis, Tenn., a well-known institution that has significant experience with pediatric melanoma.

    Between January 2000 and October 2004, the hospital has seen 22 patients under the age of 18 with melanoma.

    In October of 2003, Mark and Mylissa Horrocks rented an apartment near the hospital and lived there for three months, while three-year-old Bella began her treatment.

    Although most melanomas can just be removed with surgery, Bella's cancer had gone undiagnosed for nearly a year and a half and had progressed.

    St. Jude enrolled Bella in a study of children with Stage III melanoma.

    She received interferon injections fives times a week in her thighs for four weeks.

    The drug gave Bella severe side effects, including 105° fevers and extreme fatigue.

    After a month, doctors halved her dosage and her parents administered the shots, three times a week for the next 11 months.

    She received her final injection in October and has shown no signs of cancer for over a year.

    Bella's prognosis is good.

    Of the 15 children who participated in the St. Jude study, 12 have no evidence of disease, according to the results published in February in the journal Cancer.

    An Italian study published in March in Pediatrics found that children younger than 10 had a lower rate of relapse than older patients.

    Bella's mother believes there was nothing she could have done to prevent her daughter's cancer.

    "We believe that a child that is raised naturally is not going to have to deal with cancer. But she was breast-fed for two solid years. I made all her baby food," Mylissa Horrocks said.

    "Not a drop of formula touched her lips."

    Bella is light-skinned and fair-haired, but she doesn't have a large number of moles or freckles.

    She has no history of melanoma in her family and has never been sunburned, her mother says.

    On May 10, Bella turned five.

    She now wants to become a doctor and loves watching medical shows, her father says.

    And she puts bandages on her dolls and hooks them up to a toy IV that she received from the hospital, explaining to her parents that the dolls are recovering from surgery.

    She will receive regular checkups every three months.

    And her parents know now to watch out for the standard ABCD symptoms of melanoma: moles that are asymmetrical, have irregular borders, are many different colors, or have a diameter larger than a pencil.

    These should be checked, along with any growth that changes color, texture or size.

    "The one blessing with melanoma is that it's a skin cancer," Mylissa Horrocks says.

    "If you watch your body and you're careful, you can catch it early."

June 8, 2005 at 02:01 PM | Permalink


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