Where melanoma starts
Melanoma is a type of skin cancer. Melanoma starts in cells in the skin called melanocytes. These cells are found between the dermis and epidermis.
Melanocytes make a pigment called melanin. This gives skin its natural colour. The pigment helps to protect the body from ultraviolet light (UV radiation) from the sun.
UV radiation can cause sunburn. This is a sign of damage to the genetic material in skin cells, the DNA. Over time, enough DNA damage can cause cells to grow out of control and lead to cancer.
People who originally come from hotter climates with more sunshine tend to have naturally darker skins. They do not have more of the melanocyte cells than people with pale skin. But their melanocytes are more active and make more of the pigment.
In paler people, the pigment gives you a suntan. Exposing your skin to the sun makes the melanocytes make more pigment. The pigment is then transferred to the other skin cells to protect them against the sun’s rays.
The skin protects against heat, sunlight, injury, and infection. Skin also helps control body temperature and stores water and fat. Skin cancer is the most common type of cancer. It usually forms in skin that has been exposed to sunlight, but can occur anywhere on the body.
Skin has several layers. Skin cancer begins in the epidermis (outer layer), which is made up of squamous cells, basal cells, and melanocytes.
There are several different types of skin cancer. Squamous cell and basal cell skin cancers are sometimes called nonmelanoma skin cancers. Nonmelanoma skin cancer usually responds to treatment and rarely spreads to other parts of the body. Melanoma is more aggressive than most other types of skin cancer. If it isn’t diagnosed early, it is likely to invade nearby tissues and spread to other parts of the body. The number of cases of melanoma is increasing each year. Only 2 percent of all skin cancers are melanoma, but it causes most deaths from skin cancer.
Rare types of skin cancer include Merkel cell carcinoma, skin lymphoma, and Kaposi sarcoma.
The skin
The skin is a body organ. It does several jobs for us. It:
- protects the inside of the body from damage
- helps to keep our body temperature more or less the same
- gets rid of some waste products through sweat
The skin is made up of 2 main layers, the epidermis and the dermis.
The thickness of the epidermis and the dermis varies from about 2mm to 4mm. This depends on the part of the body the skin is covering. For example, the skin on the back is quite thick, with an epidermis and dermis of about 4mm. The skin on the face is much thinner.
Who gets melanoma
Melanoma is slightly more common in females than males. Around half of people diagnosed with melanoma in the UK each year are aged 65 and over.
Ultraviolet radiation from the sun or sunbeds is the main environmental factor that increases the risk of developing melanoma.
Other risk factors include:
- skin type
- hair and eye colour
- number of moles
- family history of melanoma
- certain medical conditions, including having a weakened immune system