Cancer occurs when the cells in a certain area of your body divide and multiply too rapidly. This produces a lump of tissue known as a tumour.

The exact reason why this happens in cases of vaginal cancer is unknown, but certain things can increase your chances of developing the condition.

Human papilloma virus (HPV)

Human papilloma virus (HPV) is the name given to a group 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 spread during sex, including anal and oral sex.

There are many different types of HPV and up to eight out of every 10 people are infected with the virus at some time during their lives. In most cases, the virus goes away without causing any harm and doesn't lead to vaginal cancer.

However, HPV is present in more than two-thirds of women with vaginal cancer, which suggests that it may increase your risk of developing the condition. 

HPV is known to cause changes in the cells of the cervix, which can lead to cervical cancer. It's thought that the virus could have a similar effect on the cells of the vagina (see below).

Abnormal cells in the cervix or vagina

You're more likely to develop vaginal cancer if you've previously been found to have abnormal cells in your:

• cervix – known as cervical intraepithelial neoplasia (CIN)
• vagina – known as vaginal intraepithelial neoplasia (VAIN)

CIN and VAIN are terms used to describe cells that are abnormal, but not different enough to be considered cancerous. Both are thought to be closely linked to having a persistent HPV infection.

The abnormal cells don't usually cause any problems themselves and may only be detected during cervical screening, but left untreated there is a small chance they could eventually become cancerous.

If you're found to have CIN or VAIN, a procedure to remove or destroy the abnormal cells may be recommended.

Diethylstilbestrol

A medicine called diethylstilbestrol is known to increase your risk of vaginal cancer. The medication was widely prescribed for pregnant women between 1938 and 1971, because it was thought it could help reduce the risk of miscarriage.

However, in 1971, researchers discovered a link between diethylstilbestrol and cancer in the children of women given the medicine. The use of diethylstilbestrol in pregnant women was then banned.

The risk of vaginal cancer associated with diethylstilbestrol is small and as it's now over 40 years since it was last used during pregnancies, cases of vaginal cancer linked to the medication are very rare.

Other possible factors

Other things that may increase your risk of vaginal cancer include:

• your age – seven out of every 10 cases of vaginal cancer occur in women over 60 and the condition is extremely rare in women under 40
• having a history of reproductive cancers, such as cervical cancer or vulval cancer – particularly if you were treated with radiotherapy
• smoking
• having HIV

Want to know more?

• Cancer Research UK: risks and causes of vaginal cancer