What is melanoma?
Melanocytes are pigmented skin cells that are located in the deep layers of the skin (epidermis). Malignant melanoma, or commonly just melanoma, is a type of skin cancer that originates from abnormal growth of melanocytes. Melanoma is the most serious form of skin cancer and grows quickly if left untreated. It can invade into deeper tissues and spread to other sites within the body.
Australia has the world's highest incidence of melanoma. In 2010, 11,405 new cases of melanoma were diagnosed in Australia.1
The cause of melanoma is due to damage to cellular DNA in melanocytes. Melanocyte cells are located in the deepest layer of the epidermis (the outer layer of skin). They produce melanin, the pigment that gives skin and hair its colour. Melanin helps to protect the skin and deeper tissues from the harmful effects of ultraviolet (UV) radiation, found in sunlight.
Melanocytes can group together in the skin, usually during childhood or adolescence, to form a mole. Most moles are safe, but melanomas can look like moles and some may develop from moles.
If UV radiation is excessive, usually through accumulated exposures throughout one's lifetime, melanocytes may begin to grow uncontrollably. When they do this, usually in those who are genetically predisposed to this condition, they become a melanoma. Melanomas have the tendency to invade nearby tissues and then spread through the body via the bloodstream or lymphatic system.â
Risk factors for developing melanomas include:
If you have a fair complexion, you are at greater risk of developing melanoma because you have less melanin to protect you against UV radiation. If you have darker skin, you have more protection, but you can still get melanoma if you do not protect your skin from the sun.
The risk of developing melanoma increases with age.
The more moles you have, the greater your risk of developing melanoma. Regular checks are a good idea if you are an adult with more than 10 moles on your arms and a total of 200 on your body.
A small number of melanoma cases occur within a family that have a genetic predisposition. If you have at least one first-degree relative with a melanoma, you may have a higher risk of also developing it.
Superficial spreading melanoma
This is the most common type of melanoma, accounting for the large majority of cases. It is more common in young people and appears more frequently on the back in males and the legs in females. It tends to grow along the top layer of skin before invading deeper into the tissue, but it first appears as a flat or raised patch with irregular borders and variation in colour.
This type of melanoma is similar to superficial spreading melanoma, in that it also initially remains contained to the skin surface. It is common in people chronically exposed to the sun, usually occurring on the sun-damaged skin of the ears, face, arms and upper body. It appears as a flat or slightly raised patch of tan, light or dark brown colouring.
Acral lentiginous melanoma
This type of melanoma also spreads superficially before invading deep in the tissue, but is different in that it usually appears on the palms of the hands, soles of the feet, or under the nails.
This type of melanoma is usually invasive by the time of diagnosis and is the most aggressive type of melanoma. Although usually black, the bump in the skin can be blue, brown, red, tan or skin-coloured. It most commonly occurs in the elderly on the trunk, arms and legs, or on the scalp of men.
Signs and symptoms
Melanoma can appear as a new mole or an unusual change in an existing mole. Therefore, it is important to get to know your skin well. The 'ABCDE signs' for a mole are a guide to self-identifying suspicious skin lesions. However, if you are concerned about any lesion, it is best to have it assessed by your doctor.
ABCDE signs for a mole
- Asymmetry – one half of the mole is unlike the other;
- Border – the border or margins of the mole is irregular or poorly defined;
- Colour – the mole has different colours, such as shades of brown, black or tan, and sometimes red, white or blue;
- Diameter – melanomas tend to be greater than 6mm in diameter (however, they can initially be much smaller), and;
- Evolving – the mole looks different from the others and is changing in size, colour or shape.
Different features of a melanoma compared to regular moles.
Methods for diagnosis
Your doctor will likely do a thorough physical examination to check all areas of your skin and scalp for any suspicious moles. If a suspicious mole is found, a specialised instrument called a dermatoscope can help magnify the lesion to allow a more detailed assessment.
If your doctor suspects a melanoma, they may perform a skin biopsy and/or refer you to a specialist (dermatologist).
A skin biopsy is a tissue sample taken for microscopic examination in the laboratory. Local anaesthetic is normally used during biopsies, but this depends on the size of the sample to be removed. In the case of an abnormal mole, an excisional biopsy is usually performed. This involves the removal of the entire abnormal mole and a small area of surrounding skin with a surgical knife.
The microscopic examination is the most accurate method of diagnosing melanoma and assessing its depth of invasion (Breslow thickness).
Breslow thickness is a measure of the deepest point at which melanoma cells invade the skin layers. It is the most reliable feature of the initial melanoma when estimating the prognosis of the condition. The Breslow thickness is also used to determine the type of treatment that might be needed. For example, a melanoma that has a Breslow thickness less than 0.76mm has a very low chance of having spread to lymph nodes, so is usually treated with a wide excision (see 'Types of treatment').
Breslow thickness is used to measure the depth of melanoma growth in the skin.
If the melanoma is suspected to have spread, then the following tests may be performed:
- A chest X-ray – melanoma can potentially spread to the lungs, which may be apparent on a chest X-ray;
- Computerised tomography (CT) scan – can identify in more detail if melanoma has present to other organs, including lung, liver and brain;
- Magnetic resonance imaging (MRI) scan – occasionally, an MRI may be needed to gain more detailed information about internal organs, and;
- Positron emission tomography (PET) – can show up potential sites of cancer spread.
Types of treatment
This surgical procedure involves cutting out the melanoma with a margin of unaffected tissue, to ensure no cancerous cells remain. If a large amount of tissue is removed, a skin flap or graft may then be needed, if the skin edges cannot be closed with sutures.
Sentinel node mapping and biopsy
This surgery is used to determine if the melanoma has spread to nearby lymph nodes. It involves the injection of a radioactive dye into the skin around the melanoma and mapping the path as the dye spreads to the local lymph nodes. These lymph nodes are removed and then assessed under a microscope to assess whether the melanoma has spread.
There are numerous other surgical procedures to treat melanomas that may have recurred in the same site, or have spread to other areas of the body.
Other therapies can be used in addition to surgical treatments, to further improve treatment outcomes. Occasionally, these therapies may be used if individuals are not suitable for surgical treatment. Often, in these situations, the aim of treatment is to control symptoms, and not necessarily for cure. The treatment options and aims can differ, based on the individual and the progression of the cancer. These include chemotherapy, radiotherapy and immunotherapy.
Chemotherapy works by attacking cancer cells and stopping their reproduction. Various medications are used, which can be administered either intravenously or orally. Melanoma has traditionally not responded well to chemotherapy, with only a handful of patients having a significant reduction in their disease.
Side effects occur because chemotherapy can also affect healthy cells. Your doctor will monitor your dosage and outcomes carefully to enable the best therapeutic outcome.
In this type of therapy, focused X-rays are applied to the area where the cancer is located. In the case of melanoma that has spread to other sites, the radiotherapy can be used to reduce the size of the cancers, which then alleviates local symptoms such as pain. This does not cure the individual of the cancer; however, it can improve their quality of life.
Some melanomas have a specific mutation in the BRAF gene, resulting in the production of a particular protein that plays an important role during the tumour growth. Medications, such as Tafinlar® (dabrafenib), have been developed to block this process, resulting in reduced tumour growth.
Keytruda® (pembrolizumab) is the latest drug to be registered in Australia for the treatment of widespread melanoma. It works by targeting a protein on the surface of immune system cells which subsequently helps them to attack the melanoma cells.
Unfortunately, these medications are not a cure for most people, but a therapy to slow the growth and spread of the disease.
Some people diagnosed with cancer seek out complementary and alternative therapies. None of these therapies are proven to cure cancer, but some can help people feel better when used together with conventional medical treatment. It is important to discuss any other treatments with your doctor before starting them.
Treatment side effects
There are several side effects that can occur as a result of treating melanoma, including:
- Bone marrow suppression – chemotherapy can stop the production of blood cells in the bone marrow. This can result in anaemia, a compromised immune system, and occasionally, bleeding issues;
- Lymphoedema – the lymphatic system drains excess tissue fluid into the bloodstream. Surgical removal of the lymph nodes can result in a build-up of fluid, leading to swelling. Massage and compression clothing can help relieve swelling;
- Nausea, vomiting and fatigue – from chemotherapy and radiotherapy;
- Altered bowel habits – constipation or diarrhoea;
- Joint and muscle pain – this occurs after a treatment session and can last a few days;
- Hair loss – some types of chemotherapy results in hair loss from the head and body. It may grow back after treatment has ended, and;
- Tingling in the hands and feet – some chemotherapeutic agents can affect the nerves. It is important to tell your doctor if you develop these symptoms.
Melanoma can metastasise. This is when the cancer spreads to other parts of the body through the bloodstream or lymphatic system, causing a harmful effect on the function of the affected organs.
Prognosis varies according to the type and stage of the melanoma. However, the overall survival rate is 91%. For those who survive the first year, this increases to 92% and for those who survive five years, the survival rate for the next five years increases to 95%.1
It is important to remember survival rates are only an indication, and are based upon the averages of previously treated patients. It is not an absolute prognosis for an individual. It is often difficult to accurately predict an individual's cure or survival rate. Constant advances in treatment are continually improving these statistics.
Exposure to UV radiation is the primary cause of melanoma. Not tanning and avoiding exposure during peak UV times2 can help reduce your risk. Using shade (trees, parasols) and wearing sunscreen, wide-brimmed hats, and long-sleeved collared shirts are good ways to block out harmful UV rays.
Last Reviewed: 03/10/2018
Reproduced with permission from Health&.
Video: Skin cancer
Skin cancer is a group of cancers that originate from several different types of skin cells. Treatment options vary, depending on the type and stage. Protective measures, such as minimising sun exposure and wearing appropriate clothing outdoors, can go a long way towards preventing skin cancer.
Skin cancer: what is it?
There are 3 main types of skin cancer: basal cell carcinoma (BCC), melanoma and squamous cell carcinoma (SCC).
Melanoma is the most serious form of skin cancer. Most melanomas arise as a new spot on previously normal skin, rather than from a pre-existing mole.
A mole is a common type of skin growth that can occur anywhere on the body. They can be flat or raised and sometimes have hair growing out of them. Typically, moles are harmless, however a change in shape, size, or colour of a mole, may call for a medical exam.
Vitiligo is a skin condition generally characterized by a patchy loss of pigment (colour) from the skin or mucous membranes on any part of the body. It is not painful or itchy, but can affect an individual’s self-image. Treatment options are available for those wanting it.