Melanoma is a type of skin cancer. Many risk factors have been linked to the disease, but one major cause is avoidable - overexposure to the sun.
Melanoma is a particular form of skin cancer. It happens when the pigment cells (the melanocytes) become cancerous. Most pigment cells are found in the skin, although melanoma can also occur in the eyes (ocular melanoma) and other parts of the body.1
There are numerous types of skin cancer, of which melanoma is one of the common types, although it is much less common than basal cell and squamous cell skin cancers. Melanoma is a rarer but more dangerous type of skin cancer than these because it is more likely to spread. It is very rare in people with dark skin.1,2
This article focuses on melanoma because it is the best known and most important skin cancer to prevent. Also, much of the information about melanoma, including in terms of treatment, also applies to the more common, but less worrying, skin cancers and pre-cancerous lesions.2
Briefly here, however, squamous cell skin cancer and basal cell skin cancer are both a type of non-melanoma skin cancer. Basal cell is the most common form, usually grows very slowly, and usually never spreads. Neither does squamous cell usually spread. Both types are also known as keratinocyte skin cancers - to do with their appearance under the microscope - and both are linked to sun exposure.2
Contents of this article:
Fast facts on melanoma
Here are some key points about melanoma. More detail and supporting information is in the body of this article.
- Melanoma is one of three common types of skin cancer, and the most dangerous form.
- Melanoma accounts for almost 10,000 of the >13,000 skin cancer deaths each year (American Cancer Society).
- Melanoma is rare compared with the other two common skin cancer types.
- Numerous risk factors have been identified for melanoma.
- Repeated overexposure to the sun is the only avoidable risk factor - not getting sunburnt is the best prevention against melanoma.
- Diagnosis of skin cancer is made initially by the appearance of the skin, and confirmed by biopsy sample.
- Self-monitoring of moles and other markings on the skin helps to detect skin cancer early.
- Treatment usually aims to completely remove skin cancer tumors, and is curative if done at the cancer's earliest stage.
Melanomas can develop on any part of the skin. Certain areas are more prone than others, however - in men, the trunk (chest and back) is most likely to be affected by melanoma; in women, legs are most commonly affected. Other common sites are the neck and face.2
Skin cancer is the most common type of cancer in the US, says the National Cancer Institute.1
Almost 70,000 Americans are diagnosed with melanoma every year, and almost a further 50,000 cases are diagnosed with an early form of the disease.1
Recent developments in melanoma
Did a risk of skin cancer drive the evolution of black skin in humans? Skin cancer has influenced skin color, according to research in February 2014.
Multiple sunburns as an adolescent increase melanoma risk by 80%. May 2014 research found that severe sunburn incidents between the ages of 15 and 20 were linked to higher risk of melanoma.
Grapefruit, orange juice linked to increased risk of melanoma. Grapefruit and orange juices are breakfast staples for many of us. But consuming these in large amounts may be putting us at higher risk of melanoma - the deadliest form of skin cancer - according to a new study published in the Journal of Clinical Oncology.
Causes of melanoma
As with all cancers, the causes of melanoma are being continually researched. Certain types of skin are more prone to melanoma than others. The following are risk factors that make people more prone to skin cancer:2,3
Change of appearance in skin moles should raise suspicion of melanoma.
- High freckle density or tendency to develop freckles after sun
- High number of moles
- Five or more atypical moles
- Presence of actinic lentigines (small gray-brown spots also known as liver spots, sun spots, or age spots)
- Giant congenital melanocytic nevus (brown skin marks present at birth - birth marks)
- Pale skin that does not tan easily and burns; light-coloured eyes
- Red or light-coloured hair
- High sun exposure, particularly if it produces blistering sunburn, and especially if sun exposure is intermittent rather than regular
- Age - risk increases with age
- Family or personal history of melanoma
- Being female
- Having an organ transplant.
Only one of the above risk factors stands out as avoidable - high sun exposure and sunburn. A report by the World Health Organization has estimated the number of early deaths caused by excessive exposure to the sun's UV (ultraviolet) radiation: 60,000 around the world in the year 2000, and many of these people died from melanoma.4
Avoiding overexposure to the sun, and sunburn, are, therefore, obvious ways to prevent unnecessary cases of skin cancer. Sunbeds are also a source of damaging UV exposure.2
Symptoms of melanoma
As with other forms of cancer, the early stages of melanoma may not produce any symptoms - which is why active surveillance is heavily promoted by cancer charities and so on. Some signs, however, may signal the disease, and changes in skin appearance are the key ones (these are also used in the diagnostic process).
The Melanoma Research Foundation has produced a web page that compares pictures of melanoma with those of normal moles. The American nonprofit organization also lists the following symptoms and signs that should prompt suspicion of skin cancer - plus a visit to the doctor:5
- Skin change - a new spot or mole, or a change in color, shape or size of a current spot or mole
- Skin sore that fails to heal
- Spot or sore that becomes painful, itchy, tender or bleeds
- Spot or lump that looks shiny, waxy, smooth or pale
- A firm red lump that bleeds or appears ulcerated or crusty
- A flat, red spot that is rough, dry or scaly.
The ABCDE examination of skin moles is also a key way to reveal suspect lesions.
On the next page we look at tests and diagnosis for melanoma as well as skin cancer prevention tips and treatments options for people with melanoma.