Risks and causes of vaginal cancer

A risk factor is anything that can increase your chance of developing a disease. Different cancers have different risk factors. There are some factors that may increase your risk of vaginal cancer.

Remember that having one or more risk factors does not mean that you will definitely get vaginal cancer. Many people with one or more risk factors never get it. And sometimes people with none of these risk factors develop vaginal cancer. Risk factors are only a guide to what may increase risk.

We don’t know the exact causes of vaginal cancer. It is a rare cancer and only about 260 new cases are diagnosed in the UK each year. That is only 1 out of every 500 cancers diagnosed in women.

Cancer starting in another place in the body such as cancer of the cervix, womb cancer or bowel cancer can spread to the vagina. This is not the same as cancer starting in the vagina. Cancer starting in the vagina is known as primary vaginal cancer. Cancer that has spread from another place in the body is called secondary cancer.

Because vaginal cancer is such a rare type of cancer, it is very difficult to carry out research involving large enough numbers of women to give any reliable results. But researchers have managed to identify several risk factors.

As women get older their risk of vaginal cancer increases. But because vaginal cancer is very rare, the increased risk is still very small. Cancer of the vagina mainly affects women over the age of 60. More than 7 out of every 10 cases (70%) occur in women over 60. It is an extremely rare type of cancer in women younger than 40, except for a particular type of vaginal cancer called clear cell adenocarcinoma. Clear cell adenocarcinoma occurs in the daughters of women who took a drug called diethylstilboestrol during pregnancy.

Human papilloma virus (HPV) is a common infection and is passed from one person to another by sexual contact. Around 8 out of 10 people (80%) in the UK are infected with the HPV virus at some time during their lifetime. For most people the virus causes no harm and goes away without treatment. It is only when the infection won't clear up that sometimes there is a problem. But most women infected with HPV don’t go on to develop vaginal cancer.

HPV is present in two thirds of women who have vaginal cancer (66%) and more than 9 out of 10 women who have precancerous changes in the vagina (VAIN). There are many different types of human papilloma virus (HPV). 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 have an increased risk of developing precancerous cell changes (VAIN) and some may develop vaginal cancer. 

Women with HPV types 16, 18 and 31, as well as some others, have a higher risk of developing genital and anal cancers. These types of HPV can cause changes in the cells covering the vagina. The changes make the cells more likely to become cancerous in time. But this can take years. Most women infected with these viruses do not develop cancer of the vagina. So other factors must also be needed. The type of HPV most strongly linked to vaginal cancer is HPV 16.

Although not designed to do so, having regular cervical screening tests will help to pick up vaginal cancer in its very early stages or in its precancerous stage (VAIN).

A condition called VAIN can mean you are more at risk of getting vaginal cancer. VAIN stands for vaginal intraepithelial neoplasia. It means there are changes to the cells in the inner lining of the vagina. These changes are not enough to make the cells cancerous. But they could become cancerous if not treated. There is information about vaginal intraepithelial neoplasia (VAIN) in this section.

If you have had cervical cancer or precancerous changes in your cervical cells, you have an increased risk of developing vaginal cancer. Precancerous cervical cell changes are also called cervical dysplasia or CIN (which stands for cervical intraepithelial neoplasia).

A large American study has shown that women who have had womb cancer have a risk of vaginal cancer that is 3 times higher than women in the general population. In women who have had radiotherapy for their womb cancer the risk is higher compared to women who did not have radiotherapy.

There may be a link between cancer of the vagina and smoking. But there have only been a small number of studies looking into this and most studies show no increase in risk amongst smokers. A recent study of women with HPV infection showed that women who smoked were more likely to develop advanced VAIN than non smokers.

Women with HIV or AIDS have an increased risk of vaginal cancers, as well as other cancers in the genital or anal area. This may be because HIV and AIDS lower immunity so that the body is less able to overcome HPV infection. But most women who have vaginal cancer do not have HIV or AIDS.

Women who have had organ transplants (such as kidney or heart transplants) have a risk of vaginal cancer that is up to 20 times higher than other women.

Diethylstilbestrol is also called DES. It is a drug that doctors sometimes gave to pregnant women in the past, to stop them having a miscarriage. The daughters of women who took DES during their pregnancy are more at risk of getting a type of vaginal cancer called clear cell adenocarcinoma.

DES was only used between 1945 and 1970 and researchers are still gathering information about its effects. It seems daughters of women who took DES are most likely to develop vaginal cancer between the ages 15 and 22. The oldest woman so far to get this type of cancer was 42 years old and the youngest girl was 7.

Clear cell adenocarcinoma is a very rare type of cancer and only 1 in 1,000 women with a mother who took DES will go on to develop it. Researchers are investigating other factors that may increase the risk and might help to explain why only 1 in 1,000 women are affected. DES hasn't been used for over 35 years now, so it is becoming less important as a risk factor.