New challenges of melanoma
Rising incidence calls for reassessment of prevention, diagnosis and treatment
The incidence of melanoma continues to rise, despite valiant efforts.
“The lifetime risk of an American developing invasive melanoma (ICD-10 C43.9) is about 1 chance in 50,” says Darrell Rigel, M.D., a clinical professor of dermatology at New York University. “And should that rate of increase continue over the next few years, the cancer will affect 1 in 40 Americans.”
When including melanoma in situ (ICD-10 D03.9) in the calculations, an American has a lifetime risk of roughly 1 in 24.
“Melanoma is a serious public health problem, with rates rising in both men and women,” says Dr. Rigel, who presented on melanoma at the 2017 Winter Clinical Dermatology Conference in Hawaii.
The highest rate of increase for melanoma is in people over the age of 50.
“This is probably due to excessive sun exposure, for which they are unable to undo all the skin damage,” says Dr. Rigel, in a post-presentation interview with Dermatology Times.
Sun protection is the most single important action a person can take to minimize skin damage.
There is also a difference between primary prevention and secondary prevention.
“Primary prevention basically protects the person from the sun by wearing sunscreen,” Dr. Rigel says. “This affects the incidence.”
Secondary prevention entails a patient visiting a dermatologist after noticing a suspicious skin spot.
“This is early detection and impacts mortality,” Dr. Rigel says.
As to which is more important – primary prevention or secondary prevention – Dr. Rigel tends to err on the side of secondary prevention.
“It is hard to change a person’s behaviors, but you can assess a person’s skin spot,” he says.
Thin and thick
The number of thin lesions is growing faster than the number of thick lesions.
“Today, about 75% of cases of melanoma are being diagnosed with lesions less than 1 mm in thickness,” Dr. Rigel says.
Because patients with thin lesions now represent the largest group that dies from melanoma, “it is particularly important to detect melanoma as early as possible,” Dr. Rigel says.
Several published papers over the last year conclude that melanoma itself can have its prognosis determined, even on thinner lesions.
Gene expression profiling can also help diagnose or predict melanoma. For example, myPath (Myriad Genetics Inc.) is a genetic test that profiles 23 genes to diagnosis whether a lesion is melanoma or not.
Similarly, DecisionDx (Castle Biosciences Inc.) is a 31-gene expression profile test to assess prognosis.
“The test is easy to use,” Dr. Rigel says. “You can actually obtain tissue from the laboratory instead of ordering a second biopsy.”
However, in reality, “wo specific genes may be predictive of melanoma,” Dr. Rigel says.