WHAT IS MELANOMA?
Melanoma is usually, but not always, a cancer of the skin. It begins in melanocytes — the cells that produce the pigment melanin that colours the skin, hair and eyes. Melanocytes also form moles, where melanoma often develops. Having moles can be a risk factor for melanoma, but it’s important to remember that most moles do not become melanoma.
General categories of melanoma:
Cutaneous melanoma is melanoma of the skin. Since most pigment cells are found in the skin, cutaneous melanoma is the most common type of melanoma. Cutaneous melanoma can be described in four main ways:
•Acral lentiginous melanoma
•Lentigo maligna Melanoma
Mucosal melanoma can occur in any mucous membrane of the body, including the nasal passages, the throat, the vagina, the anus, or in the mouth
Ocular melanoma, also known as uveal melanoma or choroidal melanoma, is a rare form of melanoma that occurs in the eye.
Unlike other cancers, melanoma can often be seen on the skin, making it easier to detect in its early stages. If left undetected, however, melanoma can spread to distant sites or distant organs. Once melanoma has spread to other parts of the body (known as stage IV), it is referred to as metastatic melanoma and is very difficult to treat. In its later stages, melanoma most commonly spreads to the liver, lungs, bones and brain; at this point, the prognosis is very poor.
What causes melanoma?
Research suggests that approximately 90% of melanoma cases can be linked to exposure to ultraviolet (UV) rays from natural or artificial sources, such as sunlight and indoor tanning beds. However, since melanoma can occur in all melanocytes throughout the body, even those that are never exposed to the sun, UV light cannot be solely responsible for a diagnosis, especially mucosal and ocular melanoma cases. Current research points to a combination of family history, genetics and environmental factors that are also to blame. Taking steps to prevent melanoma is therefore the best first step in protecting yourself and your skin. It is important to learn about all of the risk factors.
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 grey-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-coloured eyes.
•Red or light-coloured 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.
•Having an organ transplant.
Treatment 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 tumour or suspected tumour.
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).