Family doctor

Although melanoma is only one of the cancers that affect the skin, it is the most important. The other two are Squamous Cell Carcinoma (SCC) and Basal Cell Carcinoma (BCC). Although less likely to be a threat to life than melanoma, it is important to detect and treat them too as they can spread and require extensive surgery if neglected.

Melanoma is a highly malignant form of skin cancer arising from pigment cells or melanocytes. If neglected, cells often spread internally (metastasise) causing death.

The incidence of melanoma in New Zealand has been increasing alarmingly in recent years. Recent studies suggest Auckland may have the highest incidence in the world exceeding even that seen in Queensland. This cannot be explained by increased awareness, and represents a true increase.

Melanoma remains a leading cause of death in young people and melanoma deaths are increasing despite increased public awareness and concern.

As a dermatologist I see melanoma frequently, on average two cases per week. Most are early and can be reliably cured by surgery. Why then does melanoma so frequently kill? Some common misconceptions undoubtedly contribute.

Removing moles makes them turn cancerous or causes localised melanoma to spread. They are best left alone.

There is no evidence that removing a mole will cause cancer. This misconception arises from removal of melanomas too late when spread has already occurred.

I now avoid the sun there so I won't need to worry about developing a melanoma.

Most of the lifetime melanoma risk is set in childhood. Sun protection beyond this period may not protect and a melanoma could develop decades later. You should check your moles for life.

Melanoma only occurs in sun exposed areas.

Melanoma may occur in covered sites such as the buttocks and even palms and soles.

A melanoma will be itchy, raised or bleeding. My flat moles are OK.

Most melanomas are flat and have no itching bleeding or pain associated. You must watch for changes.

I have had all my large funny looking moles removed so now I will be safe or I put sunblock on my big moles.

80% of melanomas arise as a new spot in the skin and not in a pre-existing mole. Of those that do arise in a mole, it is not possible to guess which mole might turn malignant. Removing an individual mole or even large numbers of moles to avoid them turning cancerous makes no difference to your melanoma risk.

Sunbeds and a good suntan will help prevent melanoma.

Any form of suntan represents a response to injury in the skin. Sun damage and melanoma risk is cumulative.

No New Zealanders are immune but some are at particular risk:

Those with atypical (Dysplastic) moles - large numbers of moles many large and irregular in shape and colour are at particular risk.

Past or family history of melanoma especially if you have dysplastic nevi as well.

Fair skin, red hair, and tendency to burn easily.

This is especially important in children. Sun avoidance and physical protection (hats, rash suits, and adequate clothing) are most important. Make sure your children’s schools have hat rules and that these are enforced. Sun blocks avoid sunburn but it is far from clear how much they lessen skin cancer risk. Avoiding outdoor exposure in the hottest part of the day makes a lot of sense.

It is worth checking your own moles about every 2 months. Enlist some help for your back. A hand mirror can also be useful. Ideally all New Zealand teenagers and adults should have a mole check from a doctor once a year. Certain high-risk groups need more frequent checks. Mole checks need to be thorough. The annual free melanoma check day is NOT designed to do this full check.

Current mole imaging and mapping techniques are NOT a proven substitute for this examination and in my view contribute little extra. Detailed imaging is only performed on an arbitrary subset of moles. In many cases a doctor is involved only in looking at the selected images. As mentioned most melanomas arise as new "moles" and it is not possible to define which existing mole is more likely to become malignant so that recording images of moles affords little protection. There is no evidence supporting the effectiveness of mole mapping procedures. Mole mapping does not check for other forms of skin cancer (SCC and BCC) as mentioned above. In the view of most dermatologists, it is for better to have a regular check performed by someone who has seen and thus can recognise a melanoma or other type of skin cancer (e.g. dermatologist or other experienced doctor). If there is any doubt about a specific mole the only safe course of action is to cut it out.

WHAT SHOULD I LOOK FOR IN MY MOLES?

Change is the key point. Any new or changing existing mole is suspect. Melanomas are cancers and have no growth control. They are thus changing and show disordered or chaotic growth patterns.

The ABCD approach is a useful guide:

A. Asymmetry. Benign moles are round or oval and are symmetrical, while melanomas are irregular in shape with one half unlike the other.

B. Border. Benign moles have a regular border while melanomas are irregular and jagged. Benign mole - symmetrical even border, colours and less than 6mm in diameter.

C. Colour. Benign moles have only 1-2 even colours while melanomas show many shades.

D. Diameter. Most benign moles are smaller than the head of a pencil. Although melanomas start small they enlarge over weeks to months.

TREATMENT OF MELANOMA

Contrary to popular opinion, most melanomas seen are quite easily curable with minor surgery. The suspicious mole is cut out with a small margin of normal skin and sent to the pathology laboratory. If melanoma is confirmed, a further minor procedure is performed to remove a wider margin of skin to be sure no melanoma cells are left in the area. It is usually possible to do this without a skin graft. In previous times large and quite mutilating excisions were routinely performed but this is seldom necessary now.

Most melanomas have a surface spreading phase and then later start growing downwards, forming "roots". The risk of a melanoma spreading very much depends on how much downwards growth has occurred. If melanoma is detected and removed in the surface phase, cure is possible. One cannot be sure whether cells have already spread in the bloodstream with deeper melanomas.

Trials continue to see if vaccines and other treatments might help patients with more advanced melanoma but for now these remain experimental. The only certain cure for melanoma remains early detection and surgical removal.