Melanoma

Melanoma is a type of skin cancer that arises in skin cells called melanocytes.

Melanocytes sit in the top layer of skin, called the epidermis. They produce a pigment which gives skin its colour and helps protect against ultraviolet (UV) damage. When melanocytes group together in clusters, they form a non-cancerous mole.

Occasionally melanocytes begin to grow abnormally and form a melanoma. Melanoma usually occurs on parts of the body that are exposed to the sun, but rare cases occur in body parts that receive less sun exposure, such as the inside of the mouth.

Melanoma is a rare type of skin cancer, but it is the most deadly. Melanoma is particularly dangerous because it can invade deeper layers of skin and spread to other parts of the body like the lung, liver and brain.

Excluding less deadly types of skin cancer, melanoma is the third most common cancer diagnosed in Australian men and women.

The first sign of melanoma is usually a change in an existing mole, or the appearance of a new mole. Melanomas vary greatly in how they look, but many show features such as:

• asymmetry
• irregular shape or border
• uneven colour
• increased size
• itching or bleeding
• raised surface.

As not all melanomas show these classic features, it is important that a doctor checks any moles that change in shape or grow over a period of more than one month. Suspicious moles should be removed and examined by a pathologist to look for signs of melanoma.

Melanoma is caused by genetic changes in melanocytes. These genetic changes are caused by UV radiation from the sun or from other sources such as solariums.

Factors that increase the risk of developing melanoma include:

• prolonged sun exposure, particularly during childhood
• having a large number of moles, especially those with irregular shape
• having fair or freckled skin, blue or green eyes and fair or red hair
• having a previous case of melanoma
• having a family history of skin cancer, especially melanoma

If melanoma is detected early, it can usually be successfully removed by surgery. For this reason, survival from melanoma is relatively high, with 90 per cent of people alive five years after diagnosis.

Once melanoma has spread, however, the disease can be life-threatening.

Traditional chemotherapy drugs are generally not effective in treating melanoma, and until recently, there were few treatment options for advanced disease.

Several promising treatments have recently been developed for melanoma, including:

• targeted therapies that block specific proteins that drive melanoma growth
• immunotherapies that activate the body’s own immune system to fight melanoma.

These new therapies have improved survival and reduced symptoms for many people diagnosed with advanced melanoma, however there are still many challenges.

Drug resistance is a major problem for targeted therapies, with many people having a favourable initial response but then relapsing with resistant disease. Our researchers are using cutting-edge genome technology to investigate how melanomas evolve to become drug resistant. We are also developing new drugs targeting the pro-survival proteins that are often highly expressed in drug-resistant melanomas.

Our researchers are also exploring new forms of immunotherapy based on specialised immune cells called natural killer (NK) cells. NK cells patrol the body and kill damaged cells, including cancer cells and cells infected with viruses. Our researchers discovered that NK cells are essential to eliminate melanoma cells that have spread to the lungs. They are now investigating new treatments for melanoma that harness NK cells.

WEHI researchers are not able to provide specific medical advice to individuals. If you have melanoma or are supporting somebody with this disease, please contact the Cancer Council or consult your medical specialist.