What is Skin Cancer?
Skin cancer is the uncontrolled growth of abnormal skin cells. It occurs when unrepaired DNA damage to skin cells (most often caused by ultraviolet radiation from sunshine or tanning beds) triggers mutations, or genetic defects, that lead the skin cells to multiply rapidly and form malignant tumors.
What types of skin cancers are there?
The first sign of a melanoma is often a new mole or a change in the appearance of an existing mole.
Normal moles are usually round or oval, with a smooth edge, and no bigger than 6mm (1/4 inch) in diameter.
See your GP as soon as possible if you notice changes in a mole, freckle or patch of skin, especially if the changes happen over a few weeks or months.
Signs to look out for include a mole that is:
- getting bigger
- changing shape
- changing colour
- bleeding or becoming crusty
- itchy or painful
A helpful way to tell the difference between a normal mole and a melanoma is the ABCDE check-list:
- Asymmetrical – melanomas have two very different halves and are an irregular shape.
- Border – melanomas have a notched or ragged border.
- Colours – melanomas will be a mix of two or more colours.
- Diameter – melanomas are larger than 6mm (1/4 inch) in diameter.
- Enlargement or elevation – a mole that changes size over time is more likely to be a melanoma
Melanomas can appear anywhere on your body, but they most commonly appear on the back, legs, arms and face. They may sometimes develop underneath a nail.
In rare cases, melanoma can develop in the eye. Noticing a dark spot or changes in vision can be signs, although it is more likely to be diagnosed during a routine eye examination.
skin cancer (non-melanoma)
The main symptom of non-melanoma skin cancer is the appearance of a lump or discoloured patch on the skin that doesn’t heal.
The lump or discoloured patch is the cancer, sometimes referred to as a tumour.
Non-melanoma skin cancer most often appears on areas of skin which are regularly exposed to the sun, such as the face, ears, hands and shoulders.
Basal cell carcinoma
Basal cell carcinoma (BCC) usually appears as a small red or pink lump, although it can be pearly-white or ‘waxy’ looking. It can also look like a red, scaly patch.
The lump slowly grows and may become crusty, bleed or develop into a painless ulcer.
Squamous cell carcinoma
Squamous cell carcinoma (SCC) appears as a firm pink lump and may have a flat, scaly and crusted surface.
The lump is often tender to touch, bleeds easily and may develop into an ulcer.
Bowen’s disease is a very early form of skin cancer, sometimes referred to as “squamous cell carcinoma in situ”. It develops slowly and is easily treated.
The main sign is a red, scaly patch on the skin which may itch. It most commonly affects elderly women and is often found on the lower leg. However, it can appear on any area of the skin.
When to seek medical advice
If you develop a lump, lesion or skin discolouration that hasn’t healed after four weeks, see your GP. While it is unlikely to be cancer, it is best to be sure.
Causes of skin cancer
Most skin cancer is caused by ultraviolet (UV) light damaging the DNA in skin cells. The main source of UV light is sunlight.
Sunlight contains three types of UV light:
- ultraviolet A (UVA)
- ultraviolet B (UVB)
- ultraviolet C (UVC)
UVC is filtered out by the Earth’s atmosphere but UVA and UVB damage skin over time, making it more likely for skin cancers to develop. UVB is thought to be the main cause of non-melanoma skin cancer.
Artificial sources of light, such as sunlamps and tanning beds, also increase your risk of developing skin cancer.
Repeated sunburn either by the sun or artificial sources of light, will make your skin more vulnerable to non-melanoma skin cancer.
Research suggests that if you have two or more close relatives who have had non-melanoma skin cancer, your chances of developing the condition may be increased.
Certain factors are believed to increase your chances of developing all types of skin cancer, including:
- pale skin that does not tan easily
- red or blonde hair
- blue eyes
- older age
- a large number of moles
- a large number of freckles
- an area of skin previously damaged by burning or radiotherapy treatment
- a condition that suppresses your immune system, such as HIV
- medicines that suppress your immune system (immunosuppressants), commonly used after organ transplants
- exposure to certain chemicals, such as creosote and arsenic
- a previous diagnosis of skin cancer