Find out what a risk factor is, and the possible causes of vulval cancer.
What a risk factor is
Anything that can increase your risk of getting a disease is called a risk factor.
Different cancers have different risk factors. Having one or more of these risk factors doesn't mean you will get that cancer.
Many women with vulval cancer are aged 65 or over. Vulval cancers can occur in young women and they have been seen in women in their 20's. But it is extremely rare to get vulval cancer at such a young age.
Human papilloma virus (HPV) infection
We know that HPV is an important factor in the development of some vulval cancers.
A review of published studies showed that human papilloma virus (HPV) is found in 35 out of every 100 (35%) vulval cancers. It is found in over 80 out of 100 women (80%) with vulval intraepithelial neoplasia (VIN).
HPV is passed from one person to another during sexual contact. Around 80 out of 100 people (80%) in the UK will have the HPV virus at some time during their lifetime so it is a very common infection.
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. These types of the virus are called low risk types, and are rarely linked to cancer.
Research shows that HPV type 16 is the most common type of HPV found in vulval cancer, followed by HPV types 33 and 18. Infection with these types of 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. In the future, we should see a fall in vulval cancer rates. This will take some years to show up because vulval cancer can take such a long time to develop.
Chronic skin conditions and inflammation
Some long term vulval skin conditions are associated with vulval cancer.
- lichen sclerosus
- lichen planus
- paget's disease
The most common of these is lichen sclerosus. Women with lichen sclerosus may develop a condition called differentiated vulval intraepithelial neoplasia (VIN).
This is different to usual type VIN which is linked to HPV infection. Although differentiated VIN can progress to invasive cancer, 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. This 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.
Vulval intraepithelial neoplasia (VIN)
Vulval intraepithelial neoplasia (VIN) means there are precancerous changes in the top layer of the skin (epithelium) covering the vulva.
VIN is not cancer, but there is a risk that it may go on to develop into vulval cancer. This usually takes 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 by a doctor.
HPV infection is present in about 80 out of 100 women with VIN (80%).
Cervix cell changes (CIN) or 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.
This link is probably due to both cancers sharing risk factors such as HPV.
Weakened immune system
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.
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)).
Radiotherapy for womb cancer
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.
Other medical conditions
Systemic lupus erythematosus (SLE or lupus) is a chronic auto immune disease. The immune system attacks the body’s own connective tissue cells and tissues, causing inflammation and damage. People with SLE have an increased risk of vulval cancer.
A study has shown that women have an increased risk of vulval cancer if they have had psoriasis.