Melanoma is a type of skin cancer caused by changes in skin cells that make them cancerous. While many people know that too much sun exposure can lead to melanoma, your genetics, age, and family history can also play a role in your risk. Keep reading to learn more about causes and risk factors associated with melanoma.

What Causes Melanoma Skin Cancer?

Melanoma develops in your melanocytes, the specialized skin cells that make melanin. Melanin is the pigment that gives your skin its color. Normal skin cells grow and divide at a controlled rate using instructions from your DNA. Melanocytes can become cancerous when their DNA is damaged. As a result, they begin growing and dividing uncontrollably, creating a mass or tumor.

Scientists have found that both environmental factors (like sunlight) and genetic factors contribute to the risk of melanoma. Several of these factors are described below.

1. Moles

Moles — also known as nevi — are pigmented growths that form on the skin. Most moles don’t cause any problems, but it’s important to keep an eye on them over time.

If you have many moles, you’re more likely to develop melanoma. Some people have atypical moles with certain features that could point to melanoma. For example, growths may be abnormally shaped or a different color compared to other moles.

Most atypical moles never develop into melanomas, but a few do. If you have an atypical mole, your doctor may want to monitor it regularly or remove it, just to be safe.

Some people have an inherited condition with many abnormal moles. If you have lots of abnormal growths and a family member has also had melanoma, you may have familial atypical multiple mole and melanoma (FAMMM) syndrome. People with FAMMM syndrome have an extremely high risk of melanoma. They’ll need regular skin exams with a dermatologist to monitor their moles.

2. Personal and Family History of Melanoma

If you’ve previously been diagnosed with melanoma or another type of skin cancer, you’re more likely to get it again. Your chances of melanoma also increase if you have a close relative — a parent, sibling, or child — who’s also had melanoma. Around 10 percent of people with melanoma have a family member who also has the disease.

Scientists believe that the increased risk may be due to a combination of having lifestyle factors (like sun exposure) in common, similar skin tone, and shared genetics. Overall, a family history of melanoma gives you a twofold to threefold increased risk of developing melanoma. This means that if you had a 5 percent chance before, having a family history of melanoma increases your chances to between 10 percent and 15 percent.

3. Exposure to Ultraviolet Light

Have you ever spent too long outside in the sun and noticed a sunburn later? That’s because the sun’s ultraviolet (UV) rays damage your skin cells and lead to a sunburn. The DNA in melanocytes is also damaged by UV radiation, and the cells can become cancerous years later. In most cases, melanoma is caused by gene changes or mutations that are acquired during a person’s lifetime.

You may be at a higher risk of developing melanoma if you’re exposed to too much UV light.

The sun is a major source of UV rays, but it can also come from sunlamps and tanning beds. People who live at higher altitudes or spend more time outdoors are also more likely to develop melanoma.

4. Inherited Gene Mutations and Conditions

Some people have familial melanoma caused by gene mutations (changes) passed down through family members. Most of these changes occur in tumor suppressor genes. Think of a tumor suppressor gene as a brake in a car: The gene helps hold back melanocyte cell division so cells don’t grow out of control.

A tumor suppressor gene that changes or mutates can no longer do its job. The melanocytes have “lost their brakes” and can grow and divide uncontrollably.

Other inherited genetic conditions can also raise your risk of melanoma. Examples include:

• Xeroderma pigmentosum — Affects skin cells’ ability to repair damaged DNA
• Hereditary breast and ovarian cancer syndromes — Increase risks of several cancers, including melanoma
• Werner syndrome — Causes premature aging and an increased risk of cancer

5. Age and Sex

Your risk of melanoma increases over the years. The median age of melanoma diagnosis is just over 50. This means that about half of people diagnosed with melanoma are younger than 50 and half are older than 50.

However, this risk factor varies among men and women, according to the American Cancer Society: In the United States, men are more likely to be diagnosed with melanoma and develop it after 50, whereas women are more likely to develop melanoma before 50.

Younger people can also develop melanoma, especially if it runs in the family. Melanoma is one of the most common cancers in younger people under the age of 30, particularly in women.

6. Skin Tone

People with lighter skin tones are more likely to develop melanoma compared to those with darker tones. This is especially true if you have blond or red hair, green or blue eyes, and freckles. Your risk also increases if your skin burns rather than tans.

It’s important to note that just because you have darker skin doesn’t mean you can’t get melanoma. In fact, people with dark or black skin tend to develop melanoma on parts of the body that don’t usually get sunlight, such as the soles of the feet, the palms of the hands, under the nails, or even in the moist tissues lining the nose or mouth.

Read more about different types of melanoma.

7. Weakened Immune System

Your immune system works hard to destroy cancer cells before they can take hold in your body. Having certain health conditions or taking medications that weaken your immune system can raise your risk of cancers, including melanoma.

For example, if you’ve had an organ transplant, you need to take medications that stop your immune system from rejecting it. These medications also prevent your immune system from fighting off cancer cells. As a result, you may be at an increased risk of melanoma. People infected with human immunodeficiency virus (HIV) are also more likely to develop this skin cancer due to a weakened immune system.

Talk With Others Who Understand

MyMelanomaTeam is the social network for people with melanoma and their loved ones. On MyMelanomaTeam, members come together to ask questions, give advice, and share their stories with others who understand life with melanoma.

Are you concerned that you or a family member may have an increased risk for developing melanoma? Share your thoughts in the comments below, or start a conversation by posting on your Activities page.