Melanoma is a type of skin cancer which usually occurs on the parts of the body that have been overexposed to the sun. Rare melanomas can occur in parts of the skin or body that have never been exposed to the sun.
The risk of being diagnosed with melanoma by age 85 is 1 in 14 for men compared to 1 in 24 for women.
Often melanoma has no symptoms, however it can be associated with changes that relate to ‘ABCDE’ - Asymmetry, irregular Border, uneven Colour, Diameter (usually over 6mm), Evolving (changing and growing). Other symptoms include dark areas under nails or on membranes lining the mouth, vagina or anus.
Causes of melanoma
Melanoma risk increases with exposure to UV radiation, particularly with episodes of sunburn (especially during childhood).
Melanoma risk is increased for people who have:
- increased numbers of unusual moles (dysplastic naevi)
- depressed immune systems
- a family history of melanoma in a first degree relative
- fair skin, a tendency to burn rather than tan, freckles, light eye colour, light or red hair colour
- had a previous melanoma or non-melanoma skin cancer.
Screening for melanoma
Individuals at high risk of melanoma should be taught to check their skin for irregular or changing lesions, and have annual checks by a dermatologist.
Diagnosis for melanoma
If you have a suspicious spot or mole, your doctor will examine you and may use a dermascope (magnifying instrument). If the doctor suspects melanoma, a biopsy may be carried out. This may be done by your GP or you may be referred to another specialist.
Treatment for melanoma
If the excised lesion is thick, a biopsy of the first draining lymph node (sentinel node) is performed. The most important feature of a melanoma in predicting its outcome is its thickness (stage 0 is less than 0.1mm, stage I less than 2mm, stage II greater than 2mm, stage III spread to lymph nodes and stage IV distant spread). The presence of ulceration also predicts a poor outcome. If distant spread is suspected, CT scans of the chest, abdomen and pelvis are performed. The blood test LDH can sometimes be useful to assess metastatic disease.
Surgery can be curative for thin melanomas and requires that the melanoma be removed with at least 1–2cm of normal skin around it. If the draining lymph nodes are involved they are removed.
You will have a lymph node dissection or lymphadenectomy, if the melanoma has spread to the lymph nodes to remove them.
For thick melanomas some cancer centres offer high dose interferon after surgery, however many offer clinical trials of vaccines because there is no routine therapy mandated. Surgery should be the mainstay of treating relapsed melanoma if it is possible to remove all of the disease.
For widespread disease, there is no role for chemotherapy in advanced melanoma.
Therapy for advanced disease can involve targeted therapy with a BRAF inhibitor in combination with a MEK inhibitor if your tumour has an activating BRAF mutation or immunotherapy which has activity in both BRAF mutation positive and negative tumours. The oncologist involved in your care will discuss which therapies are appropriate.
Radiotherapy may be used to palliate local symptoms.
Prognosis for melanoma
An individual’s prognosis depends on the type and stage of cancer, as well as their age and general health at the time of diagnosis. Five year survival for people diagnosed with melanoma is 91%, rising to 99% if the melanoma is detected before it has spread. If spread is within the region of the primary melanoma, the five year survival is 65%, dropping to 15% if the disease is widespread and untreated.
Avoid sunburn by minimising sun exposure especially in the middle of the day when UV levels are most intense. Seek shade, wear a hat that covers the head, neck and ears, wear sun protective clothing and close-fitting sunglasses, and wear an SPF30+ sunscreen. Avoid using solariums (tanning salons).