Risks and causes of vulval cancer

Vulval cancer is a rare cancer. Less than 1,200 cases are diagnosed in the UK each year. That is less than 1 in every 100 cancers diagnosed in women.

About 3 out of 4 cases (75%) of vulval cancer are diagnosed in women aged 65 or over. But the non invasive, precancerous condition, Vaginal Intraepithelial Neoplasia (VIN), tends to be diagnosed earlier - when women are in their 30's to 50's. Early stage vulval cancers can occur in young women - they have been seen in women in their 20's. But it is extremely rare to get vulval cancer at such a young age.

Vulval intraepithelial neoplasia (VIN) means there are precancerous changes in the top layer of the skin (epithelium) covering the vulva. VIN is often divided into 3 categories - VIN1, VIN2 and VIN3. These categories are also called mild, moderate or severe dysplasia. Dysplasia means abnormal cells. Many women with VIN have HPV infection.

The most common symptom of VIN is a lasting itch that doesn't go away. Areas of skin affected by VIN can look thickened and swollen, and have red, white or dark coloured patches. VIN is not cancer, but there is a risk that it may go on to develop into vulval cancer, usually over many years. Although most cases of VIN will not develop into cancer, it is not possible to tell which will and which won’t. So everyone with this condition should have treatment, or at least close monitoring of their condition by a doctor.

A review of published studies showed that human papilloma virus (HPV) is found in about 4 out of every 10 vulval cancers (40%) and about 8 out of 10 cases (80%) of VIN. So, it is an important factor in the development of some vulval cancers.

HPV is a common infection. It is passed from one person to another during sexual contact. Around 8 out of 10 people (80%) in the UK will be infected with the HPV virus at some time during their lifetime. So it is a very common infection. Even so, more than half of all invasive vulval cancers diagnosed are not related to HPV infection. It is important to know that most women infected with HPV do not go on to develop vulval cancer. For many people the virus causes no harm and goes away without treatment. 

There are many different types of HPV and some are more likely to lead to vulval cancer than others. HPV types 6 and 11 can infect the female and male genital organs and the anal area, causing visible genital warts. Women with these types of the virus are not likely to develop vulval cancer but some women do.

Women with HPV types 16, 18 and 31, as well as some others have a higher risk of developing genital and anal cancers. Infection with these 'high risk' HPV types does not usually produce any warts or other visible signs until precancerous changes or cancer develop. 

The good news is that there is now a vaccine that can protect against HPV infection. So, in the future, we should see a fall in vulval cancer rates. This will take some years to show up, as vulval cancer can take such a long time to develop.

HPV infection is one factor that can cause cervical cancer. Some studies show that women with a previous cervical cancer, or precancerous changes in the cells of the cervix (CIN), have an increased risk of vulval cancer.

HIV (human immunodeficiency virus) is the virus that causes AIDS (acquired immune deficiency syndrome). HIV can increase the risk of vulval cancer because it weakens your immune system. So if you have HIV, you are more likely to pick up other infections, such as HPV. In turn, HPV increases your risk of getting precancerous cells in the vulva (Vulval Intraepithelial Neoplasia (VIN).

The risk of vulval cancer is also increased after organ transplant. People who have had organ transplants have to take drugs to suppress their immune system. This is to stop the body rejecting the transplanted organ.

Infection with the genital herpes virus type 2 may increase the risk of vulval cancer. This virus may interact with HPV to cause vulval cancer and other cancers in the genital and anal area. Some studies have shown an increase in risk of vulval cancer in people with genital herpes but one recent study has shown no link. So we need more research to find out whether herpes does increase the risk or not.

Women who have had radiotherapy treatment for a womb cancer have an increased risk of vulval cancer some years later. 

Researchers have found a link between vulval cancer and smoking. Being a smoker may mean that you are less able to get rid of the HPV infection from your body. It is also possible that the harmful substances in tobacco damage cells in the vulva and so lead to the development of vulval cancer.

One study has shown that women who do not drink alcohol have a lower risk of vulval cancer than women who drink some alcohol. This may be because of lifestyle factors linked to alcohol consumption and the likelihood of HPV infection.

Some long term vulval skin conditions are associated with vulval cancer. These are lichen sclerosus, lichen planus and Paget's disease. The most common of these is lichen sclerosus. Fewer than 5 in 100 women (5%) with lichen sclerosus or lichen planus develop vulval cancer. Lichen sclerosus and lichen planus cause long term (chronic) irritation of the skin of the vulva, which may be a possible cause of the increased cancer risk. Paget's disease of the vulva occurs in post-menopausal women and is very rare. A small number of women with Paget's disease may develop vulval cancer.

If you have a close relative who has had melanoma, or you have lots of unusual looking moles you are more at risk of vulval melanoma. But do bear in mind that vulval melanoma is extremely rare.

A study has shown that women have an increased risk of vulval cancer if they have had psoriasis so severe that they needed hospital treatment.

One study has shown that women have an increased risk of vulval cancer if they have a sister or mother diagnosed with cervical cancer or vulval cancer. Or if they have a father diagnosed with cancer of the airways, or the upper part of the digestive system.