Malignant melanoma is a less common but highly dangerous form of skin cancer.
When found at an early stage, melanoma has one of the highest cure rates of all cancers at more than 90 per cent. If left untreated, melanoma starts to invade into the skin. When it reaches the blood stream or the lymphatic system, it has a chance to spread to other parts of the body and often causes death.
Melanoma is a less common but most dangerous form of skin cancer. It starts in the melanocytes or pigment producing cells found in the outer layer of the skin. These cells grow out of control and form a tumour. Melanomas are often brown and black in colour but can show other shades.
Melanoma is now the 8th most common cancer in Canada. Approximately 5,500 Canadians will be diagnosed with melanoma in 2011 and 950 will die of it. Melanoma is one of a handful of cancers where the incidence in Canadians continues to grow (1.4% per year in men, 1.% per year in women).
The death rate for men with melanoma continues to rise (0.5% per year). Studies show older, fair-skinned men are more likely to die of melanoma than any other group. A lack of awareness of this disease and its common location in a hard-to-see area — the back — are likely the main reasons.
In Canada, the lifetime risk of melanoma for men is now 1 in 74. For women, it is 1 in 90. In comparison, the lifetime risk of melanoma for North Americans in the 1930s was 1 in 1,500.
Excessive exposure to ultraviolet (UV) from the sun and sunbeds plays a leading role in the development of melanoma and is the most preventable cause of this disease. Experts estimate about 90% of melanomas are associated with severe UV exposure and sunburns over a lifetime.
The best ways to protect yourself are to:
Unlike many cancers, melanoma is clearly visible on the outer surface of the skin. In the early stages, the tumour is thin, has not spread to lymph nodes, and is highly curable by surgical removal.
* Melanoma has one of the highest survival rates compared to all cancers at 90% because most melanomas are found at an early stage.
Some people are more likely to develop melanoma. Those who have:
The risk can be multiplied if you have several of these risk factors, for example, if you have unusual moles and a family history of melanoma.
People with no risk factors, and those with darker skin, can also get melanoma.
Melanoma can develop in weeks or months, or take years. It can appear as a new mole or freckle-like spot on the skin, or develop in an existing mole. Melanomas are usually dark in colour – browns and blacks, although some show a mixture of colours, including blue, grey and red.
The most common location for melanoma in men is on the back and, in women, the leg. It can also appear on the arm, scalp or face. While less common in darker-skinned people, melanoma can appear on the soles of the feet, toenails and palms of the hands.
The ABCDE of melanoma will help you to detect this disease. Look for these features:
|Asymmetry – the shape on one side is different from that on the other side|
|Border – the border or visible edge is irregular, ragged and imprecise|
|Colour – there is a colour variation, with brown, black, red, grey or white within the lesion|
|Diameter – growth is typical of melanoma. It can measure more than 6 mm, although it can be less.|
|Evolution – Look for change in colour, size, shape or symptom, such as itching, tenderness or bleeding.|
This is a tip to help you detect melanoma. Most moles on a person’s body look similar. However, melanomas look different from all other moles — the ugly duckling sign. Generally only one melanoma appears at a time, so a spot that looks or even feels different, or changes differently compared to other moles on the body, should be checked by your dermatologist or family doctor as soon as possible.
See your dermatologist or family doctor as soon as possible to have the lesion examined. A skin biopsy under local anesthesia may be needed. A pathologist or tissue specialist will then analyze the sample.
If the biopsy confirms a melanoma, further surgery will be needed to remove a safety margin around the site. This serves to remove the cancer cells that may still exist at the site of the melanoma. Since most melanomas are found at an early stage, there is a 90% survival rate.
In some cases, Mohs micrographic surgery may be used to excise the melanoma, for example if the lesion is on the face. This is a longer surgical procedure as the tissue is checked for cancer during the operation. In this way healthy skin is preserved as much as possible.
*A cancer diagnosis can sometimes cause a significant emotional shock. Patients are advised to express their concerns about the melanoma diagnosis. Some patients may occasionally need help from professional counsellors.
The main factor in determining treatment is the depth of the melanoma in the skin, as measured by the pathologist (Breslow index). The deeper the cancer, the more likely it has spread and the more likely it will recur.
Melanomas less than 1 mm thick spread very rarely. Removal of the melanoma and a surrounding margin of skin completes treatment. Other factors affecting treatment include location of the melanoma and ulceration.
If you need further tests:
If the melanoma is thicker (usually more than 1 mm), a sentinel lymph-node biopsy is often suggested to test for cancer cells in the lymph node closest to the melanoma. The results will help your doctors determine the stage of your melanoma and the treatment needed. Blood tests, a CT scan or a nuclear-medicine examination called a PET-scan may be used on occasion. (See Stages of melanoma.)
There are four main types of melanoma.
Superficial spreading melanoma accounts for about 70% of cases of this disease. These lesions tend to grow outwards, so watch for spots or moles that are spreading.
Nodular melanoma is a more dangerous form of melanoma since it grows quickly downward into the skin. It often appears on areas not usually exposed to the sun, such as the face, chest and back. It appears as a raised area and is usually very dark, but is sometimes reddish.
Lentigo maligna melanoma appears on the parts of the body constantly exposed to direct sunlight. It is frequently found among older people. It appears as an often fairly wide, flat brown patch marked by several hues of brown and black.
Acral lentiginous melanoma is the most common melanoma in dark-skinned people and those of Asian descent. It appears on the soles of feet, palms of hands and under toenails and fingernails.
There are five stages of melanoma based on the thickness and other features of the tumour. These stages provide an important guide to treatment, indicate the risk of recurrence, and determine if other tests are needed. *In Canada, most melanomas are found at an early stage
(See the description below for in situ or Stage 0 when the tumour is still limited to the outer layer of the skin and unlikely to have spread.)
Melanoma in situ is the most frequent stage, when the tumour is limited to the outer layer of the skin and has not spread. Surgery is done to remove the melanoma and the surrounding skin, which completes the treatment. The prognosis is excellent.
These are very early melanomas, less than 2 mm thick. Depending on the severity, a sentinel lymph-node biopsy is sometimes suggested. Treatment also includes a local re-excision.
The tumour is thicker than 2 mm. A sentinel lymph-node biopsy is usually suggested. After surgery there is a moderate risk of recurrence or spread to another part of the body because of the depth of the tumour.
The melanoma has spread to nearby lymph nodes. These will have to be removed.
This is an advanced stage of melanoma. The cancer has spread to another part of the body such as the lungs, liver, brain or abdomen. This situation is rare.
For Stages 3 and 4, post-surgical treatment focuses on preventing the cancer from coming back and on killing the cancer cells in the body. The following treatments, used alone or in combination, may be prescribed.