What Are Common Risk Factors For Skin Cancer?

A risk factor is something that affects the likelihood of developing a disease. Some risk factors are things that you cannot change. These are called “unmodifiable” risk factors. Examples include age, skin color, or family history. Other risk factors are things you can change or modify. The most important modifiable risk factor for skin cancer is ultraviolet (UV) light exposure.

Not everyone with a risk factor develops the disease. However, knowing what the risk factors are can help you to make changes. If you are at high risk, you may be able to take steps to detect cancer early and get treatment.

UV light exposure

UV light comes from the sun and from indoor tanning beds. UV radiation has been called a carcinogen or cancer-causing substance.¹ UV rays can damage the DNA in skin cells, which may cause harmful genetic mutations. Cancer develops when these harmful mutations lead to uncontrolled cell growth.

The type and timing of sun exposure affects skin cancer risk:

• Frequent sunburns, especially during childhood and especially for men, have been linked to melanoma.^2,3
• Long-term sun exposure, such as for outdoor workers, is associated with squamous cell carcinoma (SCC).^4,5
• Intermittent sun exposure, such as for people who occasionally enjoy outdoor activities, is associated with basal cell carcinoma (BCC) and melanoma.⁴
• Sun exposure during childhood and adolescence has been linked to BCC in some studies,⁶ but not all.⁷

Indoor tanning is not a safe alternative to outdoor sun. People who use tanning beds are at a higher risk of developing skin cancer than people who do not.¹ One study estimated that indoor tanning causes more than 419,000 cases of skin cancer each year.⁸ The American Academy of Dermatology (AAD), a major organization of dermatologists, opposes indoor tanning.⁹ In fact, the AAD has called for a ban on indoor tanning equipment. Despite the risk, indoor tanning remains popular, especially among women.⁸ About 35% of adults have tried indoor tanning, including 55% of university students and 19% of adolescents.⁸

There are many ways to protect yourself from UV light exposure. Recommendations include:

• Use a broad spectrum sunscreen with sun protection factor (SPF) 30 or higher.
• Seek shade between 10 am and 2 pm.
• Wear long sleeves, long pants, wide-brimmed hats, and sunglasses.
• Do not use indoor tanning beds.

Skin color

Non-Hispanic whites have a higher risk than blacks or Hispanics of developing skin cancer. There are about 26 cases per 100,000 non-Hispanic white persons per year, compared with 1 case per 100,000 black persons or 5 cases per 100,000 Hispanic persons.¹⁰ The risk is especially high for whites with:^2,11

• Very fair skin who freckle and burn easily
• Red or blond hair
• Blue or green eyes

Melanin is a skin pigment produced by melanocytes. It has a protective effect for people with darker skin. However, it is important to note that people with all skin tones can get skin cancer. One study showed that non-white individuals who develop melanoma have a shorter survival time.¹²

People with albinism do not make melanin. They are at high risk of skin cancer.¹¹

Age and gender

Sun exposure builds up over time, so skin cancer is more likely in older people than younger people.¹¹ Melanoma is diagnosed most frequently in people between the ages of 55 and 64 years.¹³ Basal cell and squamous cell carcinoma also become more common with age.

Overall, men are more likely than women to develop skin cancer. Each year, there are 29 new cases of melanoma per 100,000 men and 17 new cases of melanoma per 100,000 women of all races and ethnicities.¹³ However, among people younger than 50, women are more likely than men to be diagnosed with melanoma.¹⁰

Moles

Nearly all adults have moles, and most moles will never cause a problem. However, having many moles (more than 50) can increase your melanoma risk.^2,14 There are also certain types of moles that increase your risk of developing melanoma.¹⁴

Atypical moles (dysplastic nevi): These types of moles are larger than a pencil eraser and have an unusual shape or color.^2,14 They are not melanoma, but can look similar to a melanoma. Having 5 or more atypical moles puts you at a much higher risk of skin cancer compared with the general population.⁵ Atypical moles often appear on the torso, scalp, or neck. Atypical moles can run in families.

Familial atypical multiple mole-melanoma syndrome (FAMMM): People with this medical condition have more than 50 moles—some of which are atypical—and a blood relative who has had melanoma.^2,14 Having FAMMM puts a person at high risk of melanoma.

Congenital moles: A congenital mole is a mole that you are born with. Congenital moles affect about 1 out of 100 people. Having a giant congenital mole is a risk factor for melanoma.¹⁴ Another name for congenital moles is “congenital melanocytic nevi.”²

Spitz nevus: This type of mole is raised and shaped like a dome. It is often pink, but may also be red, black, or brown. Under a microscope, spitz nevi look like melanoma, but are not melanoma. Spitz nevi often appear in children, but can develop in adults too.¹⁴

Medical history

If you have had skin cancer before, you are at higher risk of developing another skin cancer.^2,11 Having a close blood relative with melanoma also increases your own risk of melanoma.² If you have two or more first-degree relatives with melanoma, your risk of skin cancer is considered very high.⁵

Infections or medications that weaken your immune system may increase your risk of skin cancer. Your immune system helps to protect your skin and other organs from developing cancer. Factors that weaken your immune system include:

1. Taking immunosuppressant medications. These medications are given to a person after an organ transplant to prevent his or her body from rejecting the organ.
2. Infection with HIV. People with HIV infection are at a higher risk of skin cancer.
3. Children who had radiation treatment for cancer have a higher risk of skin cancer. People with psoriasis who have had more than 250 treatments with psoralens and UV light have an increased risk of squamous cell skin cancer.^5,11
4. Certain inherited medical conditions are risk factors for skin cancer:
   • Xeroderma pigmentosum is a risk factor for melanoma and non-melanoma skin cancer.^2,11
   • Basal cell nevus syndrome increases the risk of BCC.¹¹
   • FAMMM increases the risk of melanoma.²

Smoking

Smokers are 1.5 times more likely than non-smokers to develop SCC.¹⁵