What is a risk factor?

A risk factor is anything that may increase your chance of having a disease. Risk factors for a certain type of cancer might include smoking, diet, family history, or many other things. The exact cause of someone’s cancer may not be known. But risk factors can make it more likely for a person to have cancer.

Things you should know about risk factors for cancer:

• Risk factors can increase a person's risk, but they don't necessarily cause the disease. 

• Some people with 1 or more risk factors never get cancer. Other people can get cancer and have no risk factors.

• Some risk factors are very well known. But there is ongoing research about risk factors for many types of cancer.

Some risk factors, such as family history, may not be in your control. But others might be things you can change. Knowing the risk factors can help you make choices that might lower your risk. For example, sun exposure is a risk factor for many types of skin cancer, and you can protect yourself from the sun.

Who is at risk for nonmelanoma skin cancer?

The most common risk factors for nonmelanoma skin cancer include:

• Sun exposure. The sun's ultraviolet (UV) rays can damage your skin and lead to skin cancer. The more time you spend in the sun, the greater your chances are of getting skin cancer. This risk is even higher for people who live closer to the equator or who live at higher altitudes, where the sun's rays are stronger.

• Use of tanning booths and sunlamps. These artificial sources of UV rays can also damage the skin, and the risk of cancer is especially high if they are used before age 30.

• Certain colors of skin, hair, and eyes. People with pale skin, red or blond hair, and green, blue, or gray eyes have an increased risk of skin cancer. Having many freckles also increases your risk. But even people with darker skin can get skin cancer.

• Personal history of skin cancer or pre-cancer. People who have had skin cancer before are at increased risk of getting it in the future. The same is true of people who have had skin pre-cancer, such as actinic keratosis.

• Older age. While skin cancer can occur at any age, the risk rises as people get older.

• Being male. Men are more likely to get nonmelanoma skin cancers than women.

• Weak immune system. People who have a weak immune system, such as people who have had an organ transplant, are at higher risk of skin cancer. Their skin cancer is also more likely to be serious.

• Exposure to arsenic. People who have been exposed to large amounts of arsenic have an increased risk of skin cancer.

• Prior radiation treatment. People who have been treated with radiation therapy have a higher risk of skin cancer in the area that was treated.

• Scars, burns, or inflamed skin. Skin cancers are more likely to develop in areas of damaged skin.

• Smoking. People who smoke are more likely to get skin cancer, especially on the lips.

•  Human papillomavirus (HPV) infection. Certain types of HPV can infect the skin in the genital area and increase the risk of skin cancer there.

• Certain rare inherited conditions. People with a condition such as basal cell nevus syndrome (Gorlin syndrome) or xeroderma pigmentosum (XP) have a much higher risk of skin cancer, starting at an early age. 

• Certain medicines. Medicines that weaken the immune system and some steroids and medicines that make the skin more likely to sunburn can increase the risk for skin cancers. These medicines include vandetanib, vemurafenib, and voriconazole. A type of medicine to treat melanoma, called BRAF inhibitors, can also increase the risk of getting new nonmelanoma skin cancers.

What are your risk factors?

Talk with your healthcare provider about your risk factors for skin cancer. He or she may advise you to have frequent skin exams. You may also need to do monthly skin exams for yourself at home. There are also things you can do that might lower your risk for skin cancer, such as protecting yourself from the sun and not using tanning beds. Talk with your healthcare provider about the best ways to reduce your risks.