Should I get genetic testing for melanoma?

Family tree: About 10% of melanomas are caused by a gene mutation (change) that passes from one generation to the next.

If you’re worried about getting melanoma, the most-serious skin cancer, you may be wondering whether you should have genetic testing. After all, genetic testing is now used find a person’s risk for many diseases.

Before getting a genetic test for melanoma, here are some facts you should know:

Few people will have a positive genetic test

The genetic test for melanoma can tell you whether you have a mutation (change) in a gene that gives you an increased risk of developing melanoma. These mutations are passed down in the family tree.

If you carry one of these mutations, your lifetime risk of getting melanoma ranges from 60% to 90%. Only about 10% of people who develop melanoma have one of these genes.

Most people get melanoma for other reasons. The sun, tanning beds, and tanning lamps give off ultraviolet (UV) rays. These rays are known to damage our skin. This damage can cause different types of skin cancer, including melanoma.

We also know that certain physical traits increase a person’s risk of getting melanoma. Physical traits that can increase your risk of getting melanoma include having skin that burns easily but rarely tans, naturally blonde or red hair, or blue or green eyes.

Having red hair and freckles may double or triple your risk of getting melanoma.

If you have 50+ moles or atypical moles, you also have an increased risk. An atypical mole looks different — more like a melanoma. Atypical moles also have a higher risk of becoming a melanoma.

Getting 5 or more blistering sunburns between the ages 15 and 20 increases your risk of getting melanoma by 80%.

You also have a higher risk of getting melanoma if you have a suppressed immune system. Some medications suppress your immune system. These include chemotherapy medications and those taken after receiving an organ transplant.

Being 50 years of age or better also increases your risk of developing melanoma.

So as you can see, people get melanoma for many reasons. It’s likely that many people who get melanoma have more than one cause at work.

Genetic testing may be recommended when you have one of these risks

In the United States, a dermatologist may consider genetic counseling and possibly genetic testing for melanoma if you have had one (or more) of the following:

• 3 or more melanomas that have grown deep into your skin (or spread), especially if one melanoma was diagnosed before your 45^th birthday
• 3 or more blood relatives on one side of your family who have had melanoma or cancer of the pancreas
• 2 or more unusual-looking moles called Spitz nevi
• 1 or more Spitz nevi and a close blood relative has (or had) mesothelioma (a type of cancer), meningioma (a type of brain tumor), or melanoma of the eye¹

Positive genetic test for melanoma can provide important information

A genetic test for melanoma can tell you about more than your melanoma risk. People who carry a mutation on a gene known as CDKN2A have a higher risk of developing melanoma, cancer of the pancreas, or a tumor in the central nervous system.

A mutation on the gene called BAP1 means a higher risk of getting melanoma, melanoma of the eye, or cancers like mesothelioma and kidney cancer.

A genetic test cannot tell you whether will develop one of these cancers.

But knowing these risks can be helpful. It can help people get needed cancer screenings.

A positive test for melanoma can also help your dermatologist monitor you for signs of skin cancer. Patients with a high risk may need more frequent skin cancer screenings. Total body photography can show changes to your moles, which can help find a melanoma in its earliest stage.

A positive test also has some drawbacks. It causes some people to feel anxious and worried. Some people worry that an insurance company may discriminate against them.

Negative test can give you a false sense of security

If the test shows that you don’t have a gene mutation for melanoma, that’s great news. But it doesn’t mean that you cannot get melanoma. More people are diagnosed with melanoma than ever before. Most of them, 90%, don’t have a gene mutation that increases their risk.

Dermatologists caution that everyone needs to protect their skin from the sun. You still need to check your skin for signs of skin cancer. And you should keep all follow-up appointments with your dermatologist.

A dermatologist can tell you about your risks

If you’re still wondering whether you should have genetic testing for melanoma, you may want to talk with your dermatologist. By talking about your concerns and risks, your dermatologist can help you decide whether this test would be helpful.

If genetic testing may be an option for you, your dermatologist can refer you to a qualified genetic counselor. A genetic counselor can talk with you about the benefits and limitations of testing.

¹ Swetter SM, Tsao H, et al. “Guidelines of care for the management of primary cutaneous melanoma.” J Am Acad Dermatol. 201. Articles in press.

Images: Thinkstock

References
Leachman SA, Carucci J, et al. “Selection criteria for genetic assessment of patients with familial melanoma.” J Am Acad Dermatol. 2009 Oct;61(4):677e1-14.

National Comprehensive Cancer Network. “NCCN Guidelines (version 1.2017) Melanoma. Last accessed March 27, 2017.

Ransohoff KJ, Jaju PD, et al. “Familial skin cancer syndromes: Increased melanoma risk.” J Am Acad Dermatol. 2016;74(3):423-34.

Swetter SM, Tsao H, et al. “Guidelines of care for the management of primary cutaneous melanoma.” J Am Acad Dermatol. 201. Articles in press.

Van Voorhees A. “What should you know about hereditary melanoma?” Dermatology World. 2016; 26(7):20-4.