Melanoma is a form of skin cancer that originates in melanocytes, the cells responsible for producing melanin, the pigment that gives skin its color. While less common than other types of skin cancer, melanoma poses a greater danger due to its potential to spread rapidly to other parts of the body if not detected and treated early. Understanding who is more susceptible to this condition is important for early detection and prevention efforts. This article explores the various demographic, genetic, environmental, and medical factors that increase an individual’s risk of developing melanoma.
Demographic Susceptibilities
Melanoma risk varies across different population groups, influenced by age, gender, and race or ethnicity.
The incidence of melanoma generally increases with age, though it is also common among people under 30. In the UK, approximately 30% of diagnosed melanoma cases are in individuals aged 75 or older.
Gender also plays a role, with males generally having a higher incidence and mortality rate from melanoma. While incidence rates are higher for females under 50, they become significantly higher for males over 50, with men over 65 having double the risk of women in the same age group. Melanoma in males is more often found on the trunk, head, and neck, while in females, it frequently appears on the legs.
Individuals with lighter skin tones have a significantly higher risk of developing melanoma, largely due to less protective melanin. For example, white individuals are approximately 20 times more likely to develop melanoma than Black individuals. While less common in people with darker skin, melanoma can still occur and is often diagnosed at a more advanced stage, leading to worse outcomes. This is partly because melanoma in individuals with darker skin tones often appears in areas with minimal sun exposure, such as the palms, soles of the feet, or under the nails (acral lentiginous melanoma).
Genetic and Personal Predispositions
An individual’s inherent biological characteristics and personal medical history influence their susceptibility to melanoma.
Skin type is a primary determinant, with those possessing fair skin, light hair (blonde or red), and light-colored eyes (blue or green) having an elevated risk. These individuals often burn easily and have difficulty tanning, indicating lower natural protection against ultraviolet (UV) radiation. The Fitzpatrick Skin Type system classifies skin based on its response to UV light, with types I and II (very fair skin) carrying the highest risk of melanoma.
The presence and characteristics of moles also factor into melanoma risk. Individuals with a large number of moles, especially over 50, have an increased likelihood of developing melanoma. Atypical moles (dysplastic nevi) are particularly important as they can resemble melanoma and indicate a higher risk, though most do not turn into cancer. People with dysplastic nevus syndrome, an inherited condition characterized by many atypical moles, face an even greater risk.
A personal history of melanoma or other skin cancers, such as basal cell carcinoma or squamous cell carcinoma, substantially increases the risk of developing subsequent melanomas. Individuals who have had melanoma before have an approximately nine-fold increased risk of another melanoma compared to the general population. A family history of melanoma, especially among first-degree relatives, also significantly elevates an individual’s risk. This increased risk can be due to shared lifestyle factors, similar skin types, or inherited genetic mutations. Specific genetic conditions, like Familial Atypical Multiple Mole Melanoma (FAMMM) syndrome, are linked to inherited mutations that can lead to a lifetime melanoma risk as high as 60-90%.
Environmental and Lifestyle Influences
External factors and behavioral choices play a substantial role in melanoma development.
The primary environmental risk factor is exposure to ultraviolet (UV) radiation from natural sunlight and artificial sources like tanning beds. UV radiation, particularly UVA and UVB rays, damages DNA in skin cells, leading to mutations that can cause uncontrolled cell growth and cancer. Damage from UV exposure is cumulative, increasing skin cancer risk over time.
Both chronic sun exposure and intermittent intense sun exposure, especially those leading to severe sunburns, significantly increase melanoma risk. Childhood sunburns are particularly impactful, with one blistering sunburn potentially doubling the risk of melanoma later in life. Recreational sun exposure, such as during vacations, may pose a higher risk than regular occupational exposure for some individuals.
The use of tanning beds is another notable risk factor, as they emit high-intensity UV radiation that damages skin cells and increases melanoma risk. Studies show that using tanning beds before age 35 can increase melanoma risk by 75%, and before age 20, the risk can increase by 47%. The belief that artificial UV radiation produces a “safer” tan is contradicted by scientific evidence, as any tan indicates DNA damage.
Geographic location also influences risk, with individuals living closer to the equator or at higher altitudes experiencing more intense UV radiation levels. For instance, Australia and New Zealand, regions with high UV exposure, have some of the highest melanoma rates globally. Occupational exposure, such as for outdoor workers, can also contribute to risk.
Immune System and Medical Conditions
An individual’s immune system and certain medical conditions can heighten their susceptibility to melanoma.
A weakened immune system compromises the body’s ability to identify and eliminate cancerous cells, making it easier for cancer to develop.
Organ transplant recipients are at an elevated risk of melanoma due to long-term use of immunosuppressive medications. Similarly, individuals with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) have a higher risk because the virus directly impairs immune function.
People undergoing certain long-term immunosuppressive therapies for autoimmune diseases may also face an increased risk. These treatments, while managing the autoimmune condition, can inadvertently weaken immune surveillance against cancerous cells.