Risks for melanoma skin cancer

Some things can affect your risk, or chance, of developing cancer. Certain behaviours, substances or conditions can increase or decrease the risk. Most cancers are the result of many risks. But sometimes cancer develops in people who don't have any risks.

Sun and indoor tanning are the main risks for melanoma skin cancer.

The number of new cases of melanoma has increased in both men and women over the past 30 years. More men than women develop it. We need more research and can't say at this time what the risk is for transgender, non-binary and gender-diverse people. The chance of developing melanoma increases with age, but it's also found in adolescents and young adults (15 to 29 years of age).

If you have a genetic condition that increases your risk for melanoma, you may need to visit your doctor more often. Talk to your doctor about your risk and if you need to have certain tests to check for melanoma.

Some of the things that increase the risk for melanoma may also cause lentigo maligna. Lentigo maligna is a very early form of skin cancer (called melanoma in situ). It is sometimes described as a precancerous condition of the skin. If lentigo maligna isn't treated, it may become melanoma that can grow into deeper layers of the skin or surrounding tissue. Find out more about precancerous conditions of the skin.

There are several things that could increase your risk for melanoma. Most of these risks can't be changed. But in some cases, there are things you can do to lower your risk.

The following can increase your risk for melanoma:

Sun and indoor tanning

Having many moles

Atypical moles

Congenital melanocytic nevi

Familial atypical multiple mole melanoma (FAMMM) syndrome

Other genetic conditions

Light-coloured skin, eyes and hair

Personal history of skin cancer

Personal history of chronic lymphocytic leukemia (CLL)

Family history of skin cancer

CDKN2A gene mutation

Weak immune system

Contact with polychlorinated biphenyls (PCBs) at work

Tall adult height

Sun and indoor tanning equipment, such as tanning beds and sun lamps, are the main risks for developing melanoma.

Having a tan means that your skin has been damaged. Sun and indoor tanning can cause sunburns, premature aging, cataracts and skin cancers.

Most cases of melanoma are caused by exposure to ultraviolet radiation (UVR) from the sun. It could be from being in the sun on and off during your lifetime or being in the sun early in your life. People who've had at least one blistering sunburn as a child or teenager have a higher risk of developing melanoma later in life. The more sunburns you've had, the greater the risk of melanoma.

Learn more about how to be sun safe.

A mole (also called melanocytic nevus) is a bump or spot on the skin that is usually brown or pink and has a smooth and regular border. Moles are made up of a group of melanocytes. Melanocytes are cells that give skin, hair and eyes their colour. Most people have a few moles.

Most moles are harmless. But you have a higher risk of developing melanoma if you have many moles.

Atypical moles (also called dysplastic nevi) look different from normal moles. They tend to be larger than 6 mm, while normal moles are usually smaller than 6 mm. Atypical moles have an uneven or irregular shape with undefined borders. A normal mole is usually round. Atypical moles often have different colours in them, which can range from pink to dark brown. They can look like melanoma, but they are not cancerous.

Having atypical moles increases your risk of developing melanoma. This risk increases with the more atypical moles you have.

Congenital melanocytic nevi are birthmarks or moles that are present at birth or develop shortly after. They may be classified as small (less than 1.5 cm), medium (1.5 to 19.9 cm) or large (covering more than 5% of the body in preteens or greater than 20 cm in teens or adults).

The larger the congenital melanocytic nevus, the greater the risk of developing melanoma.

Familial atypical multiple mole melanoma (FAMMM) syndrome is an inherited condition in which you have many moles (usually more than 50) that often look different from normal moles. A person with FAMMM also has one or more close relatives with melanoma.

People with FAMMM syndrome have a very high risk of developing melanoma.

A genetic condition is a disease caused by a change (mutation) in one or more genes. Having certain genetic conditions increases the risk of developing melanoma.

Xeroderma pigmentosum (XP) is an inherited condition that affects the skin so it can't repair damage caused by ultraviolet radiation from the sun. XP increases the risk of developing melanoma and non-melanoma skin cancers.

Werner syndrome is an inherited condition that causes the body to age very rapidly after puberty. Werner syndrome increases the risk for melanoma, bone, soft tissue and thyroid cancers.

Retinoblastoma is a type of eye cancer in children. Hereditary retinoblastoma is passed on from a parent to a child. It's caused by an inherited RB1 gene mutation. Children with hereditary retinoblastoma have a higher risk for melanoma later in life.

People with fair or light-coloured skin have a higher risk of developing melanoma than people with other skin types such as black or brown skin. People with blonde or red hair and blue, green or grey eyes also have a higher risk of developing melanoma. The risk is greater because people with these features have less melanin. Melanin is what gives colour to your skin, hair and eyes. It is believed that melanin also helps protect the skin from ultraviolet radiation. People with fair or light-coloured skin who had very bad sunburns at an early age have the highest risk for melanoma.

People with brown or black skin have a lower risk of developing melanoma, but they can still develop it. They may be more likely to develop a rare type of melanoma called acral lentiginous melanoma. This type of melanoma occurs on areas not exposed to the sun, such as the soles of the feet or palms of the hands.

People who've already had melanoma have a higher risk of developing another primary melanoma.

Having had non-melanoma skin cancer, either basal cell carcinoma or squamous cell carcinoma, is also linked with a higher risk of developing melanoma.

If you have chronic lymphocytic leukemia (CLL), you have an increased risk of melanoma. The risk of developing melanoma is greatest within 5 years of being diagnosed with CLL. The increased risk for melanoma may be due to CLL weakening the immune system.

Your risk of developing melanoma increases if one or more of your first-degree relatives has been diagnosed with melanoma. This may be due to family members having similar skin colour and sun exposure habits. It can also be due to similar genetic mutations, although this is rare.

Sometimes genes can change (mutate) so they increase the risk of developing cancer. These mutated genes can be passed down from parents to their children. If several family members have the same type of cancer, or if family members have related types of cancer, they might share an inherited gene mutation.

About 5% to 25% of families with a higher risk for melanoma have an inherited mutation in the CDKN2A gene. This gene is normally a suppressor gene, which means it helps control the growth of cancer cells. When there is a CDKN2A gene mutation, cancer may develop.

Learn more about genes and cancer.

Having a weak immune system (immunosuppression) increases your risk for melanoma. You may have a weak immune system for different reasons, including if you have HIV (the virus that causes AIDS) or if y ou've had an organ transplant and must take medicines to suppress your immune system.

Polychlorinated biphenyls (PCBs) are chemicals used in the plastics and chemical industries. Coming into contact with PCBs at work increases the risk for melanoma.

Learn more about how to be safe at work.

Being tall as an adult has been shown to increase the risk for melanoma. It's not clear why this is. It may be that because taller people have more skin cells, there is a greater risk for mutations in the skin cells that can lead to cancer.

The following have been linked with melanoma, but more research is needed to know for sure that they are risks:

• melanocortin 1 receptor (MC1R) gene mutation
• ionizing radiation
• greater birthweight
• working as a firefighter
• drinking alcohol
• PUVA therapy

Drinking coffee has been linked with a decreased risk of melanoma, but more research is needed to know for sure that it lowers the risk.

To make the decisions that are right for you, ask your doctor questions about risks. Learn how cancer can be prevented and what you can do to reduce your risk.