The most common cause of melanoma is excessive sun exposure.
This article explains the symptoms of melanoma, how it is diagnosed, and how it is treated. We also explain how best to prevent melanoma.
Contents of this article:
- 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.
What is melanoma?
Melanoma is a form of skin cancer that arises when 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.
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 (metastasize).
Squamous cell carcinoma and basal cell carcinoma are two 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 metastasizes.
Melanomas can develop on any part of the skin, but certain areas are more prone than others. 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.
According to the American Cancer Society, about 87,110 new melanomas will be diagnosed in 2017 (about 52,170 in men and 34,940 in women), and about 9,730 people are expected to die of melanoma (about 6,380 men and 3,350 women).
Symptoms of melanoma
Any changes to moles should be checked by a doctor
As with other forms of cancer, the early stages of melanoma may not produce any symptoms.
This is why actively checking skin to spot early signs of the disease is important.
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 a visit to the doctor:
- 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 (see below).
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:
- High freckle density or tendency to develop freckles after sun exposure.
- 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-colored eyes.
- Red or light-colored 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 is around 60,000 per year; an estimated 48,000 of these people died from malignant melanoma.
Avoiding overexposure to the sun and taking steps to prevent sunburn are hugely important in lowering the risk of skin cancer. This includes avoiding tanning beds as these are also a source of damaging UV rays.
Melanoma tests and diagnosis
Most cases of melanoma affect the skin, usually producing changes in existing moles. For this reason, it is possible for a person to detect the early signs of melanoma themselves by regularly examining moles and other colored blemishes and freckles.
Any changes in the appearance of the skin should prompt further examination by a doctor. The back should also be checked regularly, especially as 1 in 3 melanomas in men occur on the back; a partner, family member, friend, or doctor can help check the back and other hard-to-see areas.
Cancer doctors are most concerned with lesions that 'stand out from the crowd,' they describe five simple characteristics to look out for in the ABCDE of melanoma appearance:
Asymmetric: normal moles are often round and symmetrical, whereas one side of a cancerous mole is likely to look different from the other side - not round or symmetrical.
Border: this is likely to be irregular rather than smooth - ragged, notched, or blurred.
Color: melanomas tend not to be of one color but to contain uneven shades and colors, including varying black, brown, and tan, and even white or blue pigmentation.
Diameter: a change in the size of the mole, or a mole that is larger than a normal mole (more than a quarter inch in diameter) can indicate skin cancer.
Evolving: a change in a mole's appearance over a period of weeks or months can be a sign of skin cancer.
Doctors may use microscopic or photographic tools to help them visualize a lesion. If a doctor suspects skin cancer, the patient will be referred urgently to a cancer specialist and a biopsy will be arranged to test the lesion. A biopsy is a procedure where a sample of the lesion is taken for examination in the laboratory.
As with other types of cancer, testing for skin cancer also indicates the stage of the cancer.
Staging describes how advanced (widespread) the disease is and provides doctors with information to guide treatment decisions. The American Joint Commission on Cancer recommends the TNM staging system for skin cancers:
- T score from 0-4 based on the thickness of the tumor.
- N score from 0-3 based on how nearby lymph nodes are affected.
- M score based on metastasis (spread) to other parts of the body; M0 is no metastases, M1a, M1b, and M1c indicate varying degrees of metastasis.
The above is a brief summary of staging a cancer diagnosis, but oncologists work with much more complex detail.
Treatment and prevention of melanoma
The treatment of skin cancer is similar to that of other cancers, except that the location of the cancerous growth in the skin generally means that it is possible to completely remove the cancer (something which is much more difficult for internal cancers). As the aim of skin cancer therapy is to completely remove the cancer, surgery is the most common treatment for melanoma.
A melanoma is often surgically removed at the same time as a biopsy is taken for testing. Otherwise, the specific surgical operation involves removal of the lesion and some of the normal tissue around it - a border or margin around the tumor or suspected tumor.
In cases where a melanoma covers a large area of skin, surgery to remove the melanoma may also involve the use of skin grafts. Where the cancer is suspected to have penetrated into the lymph nodes, a lymph node biopsy may be performed.
Other, less common treatments for skin cancer include chemotherapy, photodynamic therapy (light and drug therapy - not usually used in melanoma cases), biological therapy (drugs that work with the immune system), and radiation therapy (rarely used for skin cancer).
Avoiding excessive exposure to UV radiation reduces the risk of melanoma.
Despite warnings against overexposure to the sun, it remains important to get a little sun exposure as this enables our bodies to produce vitamin D.
The time it takes to produce sufficient vitamin D is less than the time it takes to get sunburnt, meaning that enjoying the sun safely can help us to maintain optimal vitamin D without dramatically increasing the risk of skin cancer.
Avoiding excessive exposure to ultraviolet radiation can reduce the risk of skin cancer. This can be achieved by:
- Avoiding sunburn.
- Wearing clothes that protect against the summer sun.
- Using sunscreen with a minimum sun protection factor (SPF) of 15, but preferably SPF 20-30, with 4- or 5-star UVA protection.
- Not spending longer in the sun because sunscreen is used.
- Liberally applying sunscreen about half an hour before going out, and applying it again after half an hour.
- Reapplication should then be every 2 hours to maintain adequate protection.
- Avoiding the highest sun intensity between 11 am and 3 pm by finding shade. People who work outdoors need to take particular care.
- Protecting children by trying to keep them in the shade, with clothing, and by applying SPF 50+ sunscreen.
- Keeping babies out of direct sunlight.
Doctors recommend that tanning booths, lamps, and sunbeds are not used.