Skin cancer: key facts

One in three cancers diagnosed is skin cancer. There are two main types of skin cancer, melanoma and non-melanoma skin cancer (NMSC). Between two and three million people get NMSC, and around 130,000 people get melanoma skin cancer each year globally.

Melanoma skin cancer is the most serious type as it can spread to other organs very rapidly. There is a good chance that skin cancer can be cured if diagnosed and treated early.

The skin

The skin is made up of three layers:

• the epidermis
• the dermis
• the supporting subcutaneous layer of loose tissue and fat

What is skin cancer?

Skin cancer is created by an abnormal and uncontrolled growth of cells. It can either be malignant (cancerous) or benign.

Skin cancer can grow and spread to other parts of your body (through the bloodstream or the lymph system) where it may grow and form "secondary" tumours. This is called a metastasis.

There are different types of skin cancer, which are classed depending on their ability to spread to neighbouring tissues.

Non-melanoma skin cancer

There are different types of non-melanoma skin cancer including those described below.

Basal cell carcinoma (BCC)

Also known as a rodent ulcer, this is the most common form of malignant skin cancer in people with white and fair skin. It is rare in people with dark skin.

A BCC is an overgrowth of basal cells in the epidermis - usually in areas of skin that are exposed to the sun such as your head and neck. Usually, it grows slowly in the skin and does not spread to other tissues.

If left untreated a BCC will slowly grow and turn into an ulcer and grow deeper into your skin and damage nearby structures. For example, BCC on the face may erode and damage your nose or one of your ears.

Squamous cell carcinoma (SCC)

This is the second most common malignant skin cancer in people with white and fair skin. It is rare in people with dark skin.

A SCC is an overgrowth of squamous cells in the epidermis. It often occurs on areas that are exposed to the sun.

A SCC can spread into the surrounding skin, and also potentially to other parts of the body but this is not common.

Melanoma skin cancer (malignant melanoma)

Melanoma affects slightly more women than men. Melanoma is uncommon in people with dark skin.

Melanoma is an overgrowth of melanocyte cells in the epidermis. These are cells that make a pigment called melanin when your skin is exposed to the sun. Melanoma is the most serious form of skin cancer as it often spreads to other tissues or organs.

Symptoms

Different types of skin cancer can look different.

Non-melanomas such as a BCC cancer for example, can start as a small red, pink or pearly dome-shaped lump.

SCCs often appear as small scaly or crusted areas of skin with a red or pink base.

Melanoma usually starts as a dark spot or mole on your skin. If a melanoma spreads to other parts of your body, you can develop other symptoms such as swollen lymph glands (nodes).

Symptoms which may indicate skin cancer include any spot or lesion that:

• changes in size
• has an irregular shape
• has an irregular colour
• becomes inflamed
• forms an ulcer
• oozes
• feels different

Although these signs do not necessarily mean you have skin cancer, you should visit a doctor to have it checked as soon as possible.

Causes

The cause of skin cancer isn't fully understood at present. But there are certain factors that make skin cancer more likely. The main risk factor for any type of skin cancer is exposure to the intense ultraviolet light of sunshine.

Other factors that may increase your risk of skin cancer include:

• fair skin that burns easily - people with black, brown and darker olive complexions have a lower risk of skin cancer
• a family history of skin cancer
  
• skin which has a lot of moles (more than 50)
• red or fair hair and blue or green eyes
• freckles
• bad sunburn as a child
• using a sunbed
• your job - if you work outdoors you are exposed to more sunlight than if you are office-based
• increasing age - non-melanomas such as SCC and BCC are more common in people over 60 and are rare in children

Diagnosis

Your GP will examine your skin. He or she may refer you to see a specialist, such as a skin specialist (dermatologist) or a cancer specialist (oncologist) to have further tests including those listed below.

In a biopsy, your doctor will surgically remove a suspicious skin lesion or collect a small sample of tissue with a needle. The sample will be sent to a laboratory for examination to find out if it is a cancer and what type it is.

X-rays and CT (computerised axial tomography) will tell your doctor how far the cancer has spread (if at all).

In a sentinel node biopsy, your doctor will remove the closest lymph node that a melanoma skin cancer would drain into and examine it to see if cancer is present.

Treatment

Your treatment for skin cancer will depend on a number of factors such as your age and whether the cancer has spread and if so, how far. There are a number of treatments which are described below. Your doctor will advise you on which is best for you.

Surgery

Your doctor will remove the cancer and some of the normal skin surrounding it. The amount of normal skin will vary depending on the type of cancer and how deep it is in your skin - it can be one to two centimetres around where the cancer is.

Skin cancers such as BCC and SCC can also be destroyed by freezing them with liquid nitrogen. SCCs can be removed by other methods including using a drug called imiquimod (Aldara).

You may need more extensive surgery if a sentinel node biopsy shows cancer cells. This will remove the lymph nodes near to the cancer as well as the affected skin.

Treatments following surgery

Surgery may occasionally be followed by a course of radiotherapy, or you may have this instead of surgery.

The doctor may recommend interferon alfa-2b after surgery if there is a strong chance that your cancer will come back after surgery. 10Interferon alfa-2b treatment is a type of immunotherapy. This means that it helps your immune system fight the cancer.A more recent development in immunotherapy is cancer vaccines. Cancer vaccines are only used in research trials at present however, and are not widely available.

If the cancer has spread, you may be given chemotherapy.

Prevention

• To reduce your risk of skin cancer, you should minimise your exposure to the sun.
• Always use a sunscreen with a protection factor of at least 15.
• Wear protective clothing.
• Remain in the shade as much as possible - especially between 11am and 3 pm when the sun is at its strongest.
• Don't use sunbeds.
• If you notice any changes in your skin you should visit the doctor as soon as possible.

Further information

International Union Against Cancer
+41 22 809 1811
www.uicc.org/

World Health Organisation
+41 22 791 21 11
www.who.int