Squamous cell carcinoma

The most important cause is too much exposure to ultraviolet light from the sun or other sources. This can cause the DNA of skin cells (keratinocytes) in the outer layer of the skin (the epidermis) to change. Sometimes this alteration in DNA allows the skin cells to grow out of control and develop into an SCC. Ultraviolet light damage can cause SCC directly, or sometimes it can induce a scaly area called an actinic keratosis or Bowen disease. These can change into SCC if they are not treated.

Squamous cell carcinomas can also develop in skin damaged by other forms of radiation, in burns, persistent chronic ulcers and wounds, and in old scars. Certain human viral wart viruses can also contribute to its development. However, SCC itself is not contagious.

Who is most likely to have a squamous cell carcinoma?

The following groups of people are at greater risk of developing SCC:

• Immunosuppressed individuals (people with reduced immune systems) either due to medical treatment, such as methotrexate, ciclosporin and azathioprine, or due to diseases which affect immune function, including inherited diseases of the immune system or acquired conditions such as leukaemia or HIV;
• Patients who have had an organ transplant because of the treatment required to suppress their immune systems to prevent organ rejection
• People who are more susceptible to sunburn;
• People who have had significant cumulative ultraviolet light exposure, for example:
  • people who have lived in countries near to the equator, or who have been posted to work in these countries, e.g. military personnel, construction workers;
  • outdoor workers, such as builders, farmers;
  • people of advanced years, who have had a lifetime of frequent sun exposure.
• People with skin conditions such as albinism and xeroderma pigmentosum that make them more susceptible to SCC.

Are squamous cell carcinomas hereditary?

SCC is not an inherited cancer but some of the risk factors, such as fair skin and tendency to burn in the sun, are inherited.

SCCs can vary in their appearance. Most SCCs usually look scaly or crusty, raised and rough as they originate from the outer layer of the skin. Underneath the scale, there may be an ulcer that bleeds easily. Where there has been a chronic skin ulcer from other causes, it may cause the ulcer not to heal. SCCs can be sore or tender and they can bleed but this is not always the case.

SCC can occur on any part of the skin, but they are more common on sun exposed sites such as the head, ears, lip, neck and back of the hands.

Images DermNetNZ.

If your doctor thinks that the area on your skin needs further investigation, you will be referred to a specialist such as a dermatologist. The NHS aims for you to receive an appointment with the specialist within 2 weeks of referral; this may be in person or via clinical photographs being examined. SCC does not have many distinguishing features when looked at with a dermatoscope (magnified light). To confirm the diagnosis, a small piece of the abnormal skin (a biopsy), or the whole area (an excision biopsy), will be removed using a local anaesthetic and sent to a pathologist to be examined under the microscope. The results will usually be available within a week to ten days.

Can a squamous cell carcinoma be cured?

Most SCCs are low risk skin cancers and can be cured. A small number can recur locally and/or spread (metastasise) to the lymph nodes or to other parts of the body.

Surgery is usually the recommended treatment. This involves removing the SCC with a margin of normal skin around it, using local anaesthetic. The skin is then closed with stitches or sometimes a skin graft is needed. Sometimes other surgical methods are used such as curettage and cautery which involves scraping the SCC away using local anaesthetic. In some circumstances, a specialised form of surgery called Mohs micrographic surgery may be recommended to treat your SCC.

Radiotherapy can also be used to treat SCC. This involves shining a beam of X-rays onto the skin. Several sessions are usually required.

For advanced SCC, a combination of treatments may be used. For SCC that has spread to other parts of the body a combination of surgery, radiotherapy and/or chemotherapy may be used.

Examining your skin from time to time is strongly advised. If you have any concerns, you should see your general practitioner or dermatologist. In particular, look out for scaly, red and raised areas that are new, increasing in size, changing in appearance, do not heal as expected and/or form a recurrent scab.