Malignant melanoma is a skin cancer developing in pigmented (that is brown coloured) cells in the skin. It is normal for the epidermis (outside layer of skin) to contain pigment (melanin) as this protects us from damaging ultra-violet rays.
Malignant melanoma is common in New Zealand. It is thought for a number of reasons –
- We have a particularly fierce sun in New Zealand because of increasing ozone layer deficiencies.
- We have a culture of enjoying recreation in the sun and many occupations which involve substantial sun exposure.
- Our ethnic mix contains many people with skin types more suited to more cloudy climates.
- Fashion still encourages the linking of a tan with “good health” promoting questionable activities such as “sun bedding”.
Research in 2003 shows that Auckland has the highest incidence (occurrence) of malignant melanoma in the world with Brisbane a close second. This still means it is a rare disease, but nevertheless is the commonest cause when deaths from cancer in the 20-40 age group are analysed. The actual occurrence rate is 70 per 100,000 per year.
If malignant melanoma can be detected early then it is entirely curable. To date diagnostic accuracy has been poor and the medical party line has been to excise (cut out) all suspicious moles and submit these for microscopic analysis. Because of the need to avoid disastrous false reassurance many moles end up being removed only to find that they are not malignant.
This is where SIAscopy represents a major leap forward.
In 2002 a group in Cambridge UK looked into the possibility of shining intense visible light through the skin and using computer analysis to represent the reflected and absorbed light as an image which would faithfully represent the cellular types beneath the skin. This has been developed into a practical tool and the spectrum of light has been extended both into infra-red and ultra-violet beyond the visible spectrum.
Melanin absorbs ultra-violet light. Red blood vessels absorb infra-red. Intermediate frequencies have a wavelength corresponding to the sizes of collagen cells in the deeper layers of skin. These three features are represented visually in SIAscope Report (a) and SIAscope Report (b) and a fourth representation shows a magnified digital image of the skin. Previous technologies have relied solely on the magnified digital photographic image of the skin where light penetrates at best 20 microns deep into the skin. SIAscopy penetrates 2mm i.e. at least 1000 times deeper. This provides an ability to detect melanocites (pigment producing cells) which under normal circumstances are confined to the epidermis (surface layer) which have migrated deeper into the skin. This is the earliest indication of cancerous, as opposed to normal skin turnover. When all four modalities above are combined, plus detail from family and personal history, diagnostic accuracy approaches 97%.
If you have concerns about specific moles these can be SIAscoped and a more precise diagnosis achieved before any surgery is necessary. Should there be features of concern such as melanin in the dermis, excision biopsy is likely to be recommended. This means cutting round the mole under local anaesthetic with a 4mm margin. Should this prove to be a malignant melanoma a wider excision will be recommended (a 10mm margin) and depending on the thickness of the tumour other measures such as regional lymph node sampling may follow.
The more likely outcome is that moles you have worried about for years (and possibly your General Practitioner has too) can be treated to a “virtual biopsy” with SIAscopy and meaningful reassurance given.