Malignant Melanoma Skin Cancer
Contents:
General
Skin cancer is present when malignant cells develop in the outer layers of the skin. The skin protects the body against heat, light, infection, and injury. It also stores water, fat, and vitamin D.
Melanoma is the most serious form of skin cancer but is the rarest and it usually occurs in adults. If diagnosed and removed while it is still thin and limited to the outermost skin layer it is almost 100% curable. Once the cancer advances and spreads to other parts of the body, it is hard to treat and can be deadly.
Melanoma is a malignant tumor that begins in cells called melanocytes that are found between the dermis and epidermis. The cells produce the pigment melanin- the colour for skin, hair, eyes and moles.
Melanoma can be either 'invasive' or 'in situ'. Melanomas 'in situ' occupy only the uppermost part of the epidermis, the top layers of the skin. Invasive melanomas are more serious, as they have penetrated more deeply into the skin and may have travelled from the original tumor through the body. Melanoma can spread quickly to other parts of the body through the lymph system or through the blood.
Types of melanomas
Melanomas fall into four basic categories:
1. Superficial spreading melanoma is by far the most common type, making up about 70 percent of all cases. This melanoma travels along the top layer of the skin for quite a while before penetrating more deeply.
2. Lentigo maligna remains close to the skin surface for a fairly long time, and usually appears as a flat or mildly elevated mottled tan, brown, or dark brown discoloration. This type of in situ melanoma is found most often in the elderly, arising on chronically sun-exposed, damaged skin on the face, ears, arms, and upper trunk.
Lentigo maligna melanoma is the invasive form.
3. Acral lentiginous melanoma, also spreads superficially before penetrating the skin more deeply. Unlike the other forms of melanoma it usually appears as a black or brown discoloration under the nails or on the soles of the feet or palms of the hands. This type of melanoma is sometimes found in dark-skinned people. It is the most common melanoma in European Africans and European Asians, and the least common among Caucasians.
4. Nodular melanoma unlike the other forms of melanoma, it is usually invasive at the time it is first diagnosed. The malignancy is recognized when it becomes a bump. The colour is usually black, but occasionally can be blue, grey, white, brown, tan, red, or skin tone.
This is the most aggressive of the melanomas, and is found in 10 to 15 percent of cases.
Risk Factors
Those people most at risk are fair or red headed with pale skin and freckles, especially those who burn easily. People with a large number of moles are at increased risk.
Sunlight
A sun tan is skin that has been damaged by UV radiation; it produces a dark pigment called melanin to try to protect itself. It is the UVB in sunlight that causes sunburn. UVA causes the pigment in the skin to darken; it does not burn the skin but can cause damage to deeper levels of the skin. Studies have suggested that avoiding sunburns, especially in childhood and adolescence, may reduce the incidence of melanoma skin cancer.
Sun lamps/ sun beds
Sun beds emit UVA rays. Research has shown that UVA can cause all forms of skin cancer, studies indicate that sunbed use is a risk factor for melanomas and other skin cancers. People who occasionally use sun beds have more than three times the risk of developing melanoma of the eye compared to those who never use a sunbed.
It is estimated that a quarter of the young population in Britain use sun beds or lamps.
Fake tan/ self tan products
There is no evidence to suggest that fake tan products cause skin cancer. Self-tanning products contain dihydroxyacetone (DHA), a colorless sugar that interacts with dead surface cells in the epidermis, staining the skin darker. The effect is temporary, because as the dead cells naturally slough off, the colour fades.
However fake tan products do not protect the skin from the sun.
Genetics/family history
The disease is twice as common in close relatives of cases as in the general population. The genes that can make people more susceptible to melanoma have been identified. This means that tests could be developed to detect those at a genetic risk from melanoma.
Contraception pill
Taking a high dose oestrogen pill for more than 10 years may be a minor risk factor for melanoma, however there is not a great deal of evidence for this and higher dose pills are rarely prescribed now.
HRT and Pregnancy
Women get more melanomas than men, however there is no evidence that HRT or pregnancy increases the risk of melanoma.
Prevention
Avoid the midday sun
The main way to minimise the risk of skin cancer is to protect the skin from the sun. The following guidelines help to reduce the suns damaging effects.
- Minimize exposure to the sun at midday and between the hours of 10:00AM and 3:00PM.
- Apply sunscreen with at least a SPF-15 or higher, to all areas of the body which are exposed to the sun.
- Reapply sunscreen every two hours, even on cloudy days. Reapply after swimming or perspiring.
- Wear clothing that covers your body and shades your face. (Hats should provide shade for both the face and back of the neck.)
Avoid artificial sunlight
Avoid exposure to UV radiation from sunlamps or tanning salons. UV rays damage skin and can increase the risk of non melanoma skin cancer.
Protect children
Children's skin is very delicate and can burn easily from the sun's rays. The damage done to young skin may not manifest itself until they are older. It is very important to protect children adequately from the sun's harmful rays.
- Children under six months of age should be kept completely out of the sun
- Keep children older than six years of age out of the sun from 10:00am and 3:00pm when sun exposure is at its strongest
- Apply sunscreen liberally and frequently to children
Screening
The following people should ensure they visit their doctor for regular mole checks.
- People with fair skin, whose skin tends to burn quickly
- People who have a large number of abnormal moles
- People with a long history of sun exposure
There is no national screening programme in the UK. Europe?
Symptoms
The following can be warning signs of melanoma:
- change in the size, shape, or colour of a mole
- oozing or bleeding from a mole
- A mole that feels itchy, hard, lumpy, swollen, or tender to the touch
- Melanoma can also appear on the body as a new mole
Men most often get melanoma on the trunk (the area of the body between the shoulders and hips) or on the head or neck; women most often get melanoma on the arms and legs.
Diagnosis
The doctor will examine the skin carefully to see if there are signs of skin cancer. If a mole or pigmented area looks abnormal, the doctor will cut it out and a specialist will look at it under the microscope to see if it contains cancer cells.
If the diagnosis is melanoma, the doctor needs to learn the extent, or stage, of the disease before planning treatment.
Staging Melanoma
Staging is a process to learn how thick the tumor is, how deeply the melanoma has invaded the skin, and whether melanoma cells have spread to nearby lymph nodes or other parts of the body.
The doctor may remove nearby lymph nodes to check for cancer cells. A physical exam will be carried out and if the tumor is thick chest x-rays, blood tests, and scans of the liver, bones, and brain may be asked for.
Treatment
Treatment depends on where the melanoma is and how advanced the cancer has become. People with melanoma will have surgery and may have chemotherapy, biological therapy, or radiation therapy in addition patients may have a combination of treatments.
Surgery
Surgery is the usual treatment for melanoma. The surgeon removes the tumour and a rim of normal tissue around it. This procedure reduces the chance that cancer cells will be left in the area. The width and depth of surrounding skin that needs to be removed depends on the thickness of the melanoma and how deeply it has invaded the skin.
If a large area of tissue is removed, the surgeon may do a skin graft, using skin from another part of the body to replace the skin that was removed.
Lymph nodes near the tumor may be removed because cancer can spread through the lymphatic system. If cancer cells are found in the lymph nodes it may mean that the disease has also spread to other parts of the body.
Two procedures are used to remove the lymph nodes:
Sentinel lymph node biopsy
A radioactive substance is injected near the melanoma. The surgeon follows the movement of the substance on a computer screen. The first lymph node(s) to take up the substance is called the sentinel lymph node(s). The surgeon removes the sentinel node(s) to check for cancer cells.
If a sentinel node contains cancer cells, the surgeon removes the rest of the lymph nodes in the area. However, if a sentinel node does not contain cancer cells, no more lymph nodes are removed.
Lymph node dissection
The surgeon removes all the lymph nodes in the area of the melanoma.
Therapy may be given after surgery to kill cancer cells that remain in the body. This treatment is called adjuvant therapy.
Side effects of surgery
The side effects of surgery depend on the size and location of the tumor and the extent of the operation. Although patients may have some pain during the first few days after surgery, this can be controlled with medicine.
To avoid causing large scars, doctors remove as little tissue as they can (while still protecting against recurrence). In general, the scar from surgery to remove an early stage melanoma is a small line (often 2 to 4 cms long), and it fades with time. Although skin grafts reduce scarring caused by the removal of large growths, these scars will still be quite noticeable.
Surgery to remove the lymph nodes from the underarm or groin may damage the lymphatic system and slow the flow of lymphatic fluid in the arm or leg. Lymphatic fluid may build up in a limb and cause swelling (lymphedema). It is harder for the body to fight infection in a limb after nearby lymph nodes have been removed, so the patient will need to protect the arm or leg from damage that may lead to infection.
Chemotherapy
Chemotherapy, the use of drugs to kill cancer cells, is sometimes used to treat melanoma. The drugs are usually given in cycles: a treatment period followed by a recovery period, then another treatment period, and so on. People with melanoma may receive chemotherapy in one of the following ways:
By mouth or injection
Either way, the drugs enter the bloodstream and travel throughout the body.
Isolated limb perfusion (also called isolated arterial perfusion)
For melanoma on an arm or leg, chemotherapy drugs are put directly into the bloodstream of that limb. The flow of blood to and from the limb is stopped for a while. This allows most of the drug to reach the tumor directly. Most of the chemotherapy remains in that limb.
Side effects of chemotherapy
The side effects of chemotherapy depend on the specific drugs and the dose. Anticancer drugs affect both cancer cells and healthy cells that divide rapidly, especially blood cells, cells in hair roots and cells that line the digestive tract.
Biological therapy /biotherapy or immunotherapy
Biological therapy is a form of treatment that uses the body's immune system to fight cancer or to reduce side effects caused by some cancer treatments. Biological therapy for melanoma uses substances called cytokines. The body normally produces cytokines in small amounts in response to infections and other diseases. Today, using innovative techniques, scientists can produce cytokines in large amounts. In some cases, biological therapy given after surgery can help prevent melanoma from recurring. For patients with melanoma that has spread or a high risk of recurrence, interferon alpha and interleukin-2 (also called IL-2 or aldesleukin) may be recommended after surgery.
Side effects of biological therapy
The side effects of biological therapy vary with the type of treatment. These treatments may cause flu-like symptoms, such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Patients may also get a skin rash. These problems can be severe, but they go away after treatment stops.
Radiation therapy / Radiotherapy
Radiation therapy uses high-energy rays to kill cancer cells. A large machine directs radiation at the body. Treatment may last five days a week for several weeks. Radiation therapy may be used to help control melanoma that has spread to the brain, bones, and other parts of the body. It may shrink the tumor and relieve symptoms.
Side effects of radiation therapy
The side effects of radiation therapy depend on the amount of radiation given and the area being treated. Side effects that may occur in the treated area include red or dry skin and hair loss. Radiation therapy also may cause fatigue, in most cases, side effects are not permanent.
Statistics
World
- More women than men develop melanoma.
- Countries with hotter climates and large immigrant white populations have some of the highest incidence rates of malignant melanoma.
- Australia and New Zealand have very high incidence rates of skin cancer. This is because of the high level of light skinned, Northern European migrants who are exposed to high levels of UV radiation.
- White people are 40 times more likely to develop malignant melanoma than those with darker skin that have natural protection.
- Malignant Melanoma is relatively rare in black populations although worldwide 1 in 5 cases diagnosed are in black African or Asian people.
UK
- The incidence of malignant melanomas in the UK have doubled over the past 20 years.
- Melanoma claims 1,600 lives a year in the UK.
- It is estimated that in the UK 80% of melanomas of the skin are caused by exposure to the sun.
Trends
In the UK the incidence rates of malignant melanoma have been rising. This is thought to reflect the fact that more and more Britons are travelling abroad for holidays in the sun. Rates in Australia and New Zealand appear to be levelling thanks to successful sun awareness campaigns.
Socio-economic
The incidence of malignant melanoma is slightly higher among affluent groups although the prognosis is also better for this group.
Survival
Survival prospects depend on early diagnosis and the thickness of the tumour when it is discovered. Women have a greater survival rate than men. There has been a continuous improvement in survival rates over the past few years.
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