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Melanoma health centre

Squamous cell skin cancer

Squamous cell skin cancer is the second most common type of skin cancer and can cause significant problems if left untreated.

There are two main categories of skin cancer: melanoma (the most dangerous type that also spreads quickly) and non-melanoma. Squamous cell skin cancer is one of the non-melanoma skin cancers (basal cell skin cancer is another). Non-melanoma skin cancers are less dangerous than melanoma, but they are also more common. About 20% of diagnosed skin cancer is squamous cell skin cancer.

How does squamous cell skin cancer occur?

Too much exposure to ultraviolet light can lead to the development of squamous cell skin cancer. This can happen when spending too much time in the sun or using sunbeds. The exposure can be accumulative over a long term or it can be from short periods of intense sun exposure and burning. The skin damage can occur years before the cancer develops.

When certain cells in the epidermis layer of the skin are exposed to ultraviolet light, they can start to grow out of control. The epidermis is the outer layer of skin that protects your body from infections. Flat squamous cells lie within this layer just under the surface of the skin (basal cells form the innermost cells of this layer).

Normally, there is a cycle where skin cells flake off after about 40 days and are replaced by new cells. However, if the squamous cells are damaged, this cycle is disrupted and the cells keep multiplying without flaking off. These cells can eventually form into a lump known as a tumour.

Although these abnormal lumps can occur anywhere on the body, they usually occur in areas that have been repeatedly exposed to the sun such as the ears, lips or other areas on the head, the neck and the back of the hands. They can also appear where the skin has been damaged. Though this form of cancer doesn't normally spread, it can do.

What are the symptoms of squamous cell skin cancer?

Squamous cell cancer appears on an area of skin as a pink hard lump that may be tender to the touch (but if small there may be no pain) or as a patch of flaky scales or crusty area with a red inflamed base that may not heal and form an ulcer. It can sometimes bleed easily. Squamous cell skin cancer can take many years to form (although it grows faster than basal cell skin cancer).

Who gets squamous cell skin cancer?

This type of cancer is not hereditary, but some of the traits that make getting it more likely are. So if fair skin, blue eyes or freckles run in your family, you have a greater risk. The more often skin is exposed to ultraviolet light, the greater the risk there is of developing squamous cell skin cancer. People who fall into the following categories are more at risk of getting squamous cell skin cancer:

  • Older people, whether or not they avoided the sun
  • Younger people who are in the sun a lot
  • People who spend a lot of time outdoors including builders, farmers, surfers and sailors
  • Anyone who uses sunbeds or sunlamps a lot
  • People who have fair skin, light-coloured hair and eyes, or who burn easily
  • People who have a large number of moles or freckles
  • People with psoriasis who have had ultraviolet treatments
  • Anyone who has damaged skin such as ulcers, burns, scars, chronic wounds or skin that has been damaged by X-rays
  • Anyone with solar keratosis (or actinic keratosis), a type of skin damage from the sun in which there are flaky patches that may be raised, harder than the skin around them and that are red, pink or brown
  • Those who have had any form of skin cancer before
  • Anyone with a weakened immune system from taking medication after an organ transplant or to treat leukaemia or a lymphoma
  • People working with X-rays or who were given X-ray radiation in the 1940s and 1950s to treat acne and other skin conditions
  • People working with certain chemicals such as arsenic, soot, tar, metal ore or insecticides (although better safety measures are making this less common today)
  • Anyone born with the inherited disorder known as xeroderma pigmentosum, in which the cells cannot repair sun damage to the skin

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