Sun and skin – a dangerous combination
Box 4 | Diagnosing skin cancer
The main way in which skin cancer is detected is by expert checking of marks on the skin. In the summer, popular beaches sometimes have mobile skin cancer vans where people can go for a check-up.
Suspected basal cell or squamous cell carcinomas need to be removed by laser or cauterising. Melanomas, being much more serious, require surgical excision.
Of the three cancer types, the diagnosis of melanoma is clearly the most important.
The danger signs in moles or pigmented spots are:
Asymmetry of the mark
Border is irregular, unlike a normal mole
Colour is variable (could be blue, grey or pink as well as brown and black)
Diameter is often greater than 5 millimetres.
At first, melanomas are flat and they grow outwards (radially). At this stage they cannot send out metastases (clumps of cancer cells) into the rest of the body, so they are not lethal. Later, they develop a raised part in the middle. This shows that they are now enlarging upwards and downwards – and thus spreading beneath the skin into the lymphatic and blood systems. They can therefore metastasise.
Diagnosis of melanoma is usually confirmed by a biopsy – a piece of the suspected cancer is taken and checked in the lab. If positive, the whole area must then be cut out, ensuring that no cancer cells remain lower down in the skin. Even when the removed area is free of remaining melanoma cells it does not mean that microscopic clumps of cancerous cells may not have been released. These may grow and show up in later life. (Recent Australian research may enable melanoma diagnosis to be made without the need for a biopsy, see Box 5.)
Once a melanoma has been detected and removed, the affected person must remain vigilant because people who have had one melanoma are quite likely to develop another.
Boxes
Box 1. The ultraviolet family
Box 2. Types of skin cancer
Box 3. The molecular mechanisms of skin cancer
Box 5. Australian research
Box 6. Sunblocks and sunscreens
Related site
Skin cancer diagnosis and treatment (SunSmart)
Page updated March 2006.