A squamous cell carcinoma is a malignant tumour of the squamous epithelial cells. Squamous cells are flat and look like fish scales (‘squamous’ means ‘scaly’).

Squamous cells make up most of the cells in the outer layer of the skin (the epidermis), the passages of the respiratory and digestive tracts, and the linings of the hollow organs of the body, so squamous cell carcinoma can occur in many different organs including the skin, lips, mouth, oesophagus, lungs, bladder, prostate, vagina and cervix.

The rim of the ear and the lower lip are especially susceptible to squamous cell carcinomas. These cancers also tend to occur where the skin has been injured, for example, burns, scars and sores that take a long time to heal or on skin that has been exposed to X-rays or chemicals.

How common is squamous cell carcinoma?

Squamous cell carcinoma is the second most common type of skin cancer. Sunlight is responsible for over 90 percent of all skin cancers, including squamous cell carcinomas, so squamous cell carcinomas usually occur in areas exposed to the sun. Research shows that it is specifically the UVB rays that cause squamous cell carcinomas.

What’s the risk?

The risk of metastasis is greater than with basal cell carcinomas, but most squamous cell carcinomas aren’t serious if they are caught early. Research shows that, while about 96 percent are localised, the remaining four percent can metastasise (spread to other organs) and become life-threatening. Even if they do not metastasise, if left untreated, squamous cell carcinomas can cause serious local disfigurement.

What does it look like?

Squamous cell tumours are thick, rough, scaly and shallow when they develop. Sometimes they form a little ulcer or wart within the crusted surface. Any bump or open sore that’s not healing in an area of inflamed or scaly skin indicates the possibility of squamous cell carcinoma and should be checked out.

How is it treated?

If a doctor is at all concerned, a biopsy will be done to check if the lesion is squamous cell carcinoma. A biopsy involves removing a piece of the affected tissue and looking at it under a microscope. If tumour cells are present, treatment is required. The type of treatment depends on how big the tumour is, its location and how much it has spread

Nature of Science

When scientists take a biopsy of tissue, they need to prepare it for examination under the microscope. When detecting cancer, they are particularly interested in the chromosomes that are in the nucleus, so they use special stains and techniques to make them show up.

The most common form of treatment for squamous cell carcinomas is surgical removal. Radiation therapy may help reduce the size of the tumour. Chemotherapy can be used if surgery and radiation fail, but it is not usually very successful for squamous cell carcinomas.

Anyone who has had a squamous cell carcinoma has an increased chance of developing another. This is because squamous cell carcinomas are usually the result of damage the skin has already received from the sun, and this damage cannot be reversed. Damaged skin is more likely to develop carcinomas. Having had a basal cell carcinoma (the most common form of skin cancer) also makes it more likely that a squamous cell carcinoma will develop, again because both these types of skin cancer are usually caused by excessive sun exposure.

    Published 29 July 2008