Vulval cancer - Causes of vulval cancer

Exactly what causes the cells of the vulva to become cancerous is unclear although there are a number of things known to increase the risk of developing vulval cancer. 

These are:

• age - around three out of four cases of vulval cancer develop in women aged 65 or over
• human papilloma virus (HPV)
• vulval intraepithelial neoplasia (VIN)
• skin conditions that can affect the vulva, such as lichen sclerosus (see below)
• smoking

Human papilloma virus (HPV)

Human papilloma virus (HPV) is the name given to a family of viruses that affect the skin and the moist membranes that line the body, such as those in the cervix, anus, mouth and throat.

HPV is known to cause changes in the cells of the cervix, which can lead to cervical cancer. It's also thought that the virus could have a similar effect on the cells of the vulva. One expert has estimated that around 30% of vulval cancer cases are associated with an HPV infection.

The HPV virus is spread during sexual intercourse, including anal and oral sex and is thought to be one of the leading causes of vulval cancer in younger women.

Vulval intra-epithelial neoplasia (VIN)

Vulval intra-epithelial neoplasia is what's known as a pre-cancerous condition.

This means there are changes to the biological make-up of certain cells which are not the same as new cancers but could potentially lead to the formation of a new cancer at a later date.

Symptoms of vulval intra-epithelial neoplasia are similar to that of vulval cancer and include:

• persistent itchiness in the vulva
• a burning sensation when passing urine
• raised patches of skin on in the vulva that can be red or white

There are two types of vulval intra-epithelial neoplasia (VIN):

• usual VIN or undifferentiated VIN – this usually affects women aged 35 to 55 and is thought to be caused by an HPV infection
• differentiated VIN or dVIN – this is a rarer type, usually affecting older women aged 55 to 85 and is associated with skin conditions that affect the vulva (see below)

VIN can be treated by removing affected areas of skin or, in some cases, using a cream to help kill abnormal cells.

For more information, see:

• Cancer Research UK - current state of research into vulval cancer
• the British Society for the Study of Vulval Disease (BBSVD) - Vulval intra-epithelial neoplasia (VIN)

Skin conditions

Several skin conditions can affect the vulva, two of them being lichen sclerosus and lichen planus .

Both conditions cause similar symptoms - they cause affected areas of skin to become very itchy and sore and lead to the development of a red raised rash.

The causes of both conditions are unknown.

It is estimated that around 3-5% women who develop one of these conditions will go on to develop vulval cancer.

Smoking

Smoking increases your risk of developing vulval cancer.

One study found that women who smoked were twice as likely to develop vulval cancer than non-smokers.

The chemicals in tobacco smoke are known to cause damage to the cells of the body. Smoking can also weaken your immunity (defence against infection), making you more vulnerable to the harmful effects of a HPV infection.

How cancer develops

Cancer begins with a change in the structure of DNA. DNA provides our cells with a basic set of instructions, such as when to grow and reproduce.

A change in DNA structure is known as a mutation, and it can alter the instructions that control cell growth.

This means that the cells continue to grow instead of stopping when they should, producing a lump of tissue called a tumour.

How vulval cancer spreads

There are three ways that vulval cancer can spread:

• directly - spreading out of the tissue of the vulva and into surrounding parts of the body such as into the inside of the vagina or urethra
• via the lymphatic system -  the lymphatic system is a series of nodes (or glands) and channels that are spread throughout your body, much like your blood circulation system (see below)
• via the bloodstream into distant organs such as the lungs, brain, liver and bones - this generally only happens in advanced vulval cancer after the cancer cells have spread to multiple lymph nodes

Cancer that has spread to other parts of the body is known as metastatic cancer.