Melanoma is not the most common type of skin cancer, but it is the most serious. There are many risk factors for melanoma, including one major risk factor that is largely avoidable - overexposure to the sun.
Melanoma is a form of skin cancer that arises when the pigment-producing cells (melanocytes) mutate and 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, such as the intestines (this is rare). It is very rare in people with dark skin.1,2
Melanoma is just one type of skin cancer, and is much less common than basal cell and squamous cell skin cancers. However, melanoma is an especially dangerous type of skin cancer because it is more likely to spread. 1,2
This article focuses on melanoma because it accounts for the majority of deaths from skin cancer each year. Much of the information regarding the prevention and treatment of melanoma also applies to the more common, but less deadly, skin cancers and pre-cancerous lesions.2
Squamous cell carcinoma and basal cell carcinoma are two such types of non-melanoma skin cancer. Basal cell is the most common form and usually grows very slowly, rarely spreading beyond the skin. Squamous cell carcinoma also rarely metastasises. Both types are known as keratinocyte skin cancers due to their involvement of keratin-producing skin cells and their appearance under the microscope. Like melanoma, squamous cell and basal cell carcinomas 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 the rarest, but the most dangerous, form of three common types of skin cancer.
- Melanoma accounts for just 2% of skin cancer cases but almost 10,000 of the >13,000 skin cancer deaths each year (American Cancer Society).
- Numerous risk factors have been identified for melanoma, and the incidence appears to be increasing for people under the age of 40, especially in women.
- Repeated overexposure to the sun is the major avoidable risk factor for melanoma - not getting sunburnt is the best prevention against skin cancer.
- 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 with early detection of skin cancer.
- 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, the legs are the most common site of melanoma. Other common sites are the neck and face.2
Skin cancer is the most common type of cancer in the US, according to the National Cancer Institute.1
According to the American Cancer Society, about 73,870 new melanomas will be diagnosed in 2015 (about 42,670 in men and 31,200 in women), and about 9,940 people are expected to die of melanoma (about 6,640 men and 3,300 women). Almost a further 50,000 cases are diagnosed with an early form of the disease.1
Recent developments in 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.
A new study has defined a subgroup of mutations that are present in a significant number of melanomas and identifies a new major player. In describing their findings in the journal Nature Genetics, researchers hope they will lead to more targeted therapies for this most aggressive skin cancer.
While people with more than 50 moles may be at higher risk of developing melanoma, people who have fewer moles may be at greater risk of developing more aggressive melanoma.
Immunotherapy has received a boost as a treatment approach for cancer, in light of research carried out by a group of international scientists led by a team at the University of California-San Francisco.
When we think of the word "antioxidant," we often associate it with health and vitality. A new study conducted in mice, however, suggests that antioxidants can actually double the rate of melanoma metastasis.
The number of moles on one's right arm could be used to predict the risk of melanoma - the deadliest form of skin cancer - according to a new study by researchers from King's College London in the UK.
Causes of melanoma
As with all cancers, research is ongoing into the causes of melanoma. People with certain types of skin are more prone to developing melanoma, with the following factors associated with an increased incidence of 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 estimated that the number of early deaths worldwide caused by excessive exposure to the sun's UV (ultraviolet) radiation was 60,000 in the year 2000; many of these people died from melanoma.4
Avoiding overexposure to the sun, and taking steps to prevent sunburn, are hugely important in lowering the risk of skin cancer. This includes avoiding the use of tanning beds as these are also a source of damaging UV rays.2
Symptoms of melanoma
As with other forms of cancer, the early stages of melanoma may not produce any symptoms. This is why active surveillance is heavily promoted by cancer charities and public health organisations, so as to spot early signs of the disease. Changes in the appearance of the skin are key indicators of melanoma and 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. This American non-profit organization also lists the following symptoms and signs that should prompt suspicion of skin cancer and necessitate 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.