A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for cancer of the lung and many other cancers. But risk factors don't tell us everything. Having a risk factor, or even several, does not mean that you will get the disease. And not having any risk factors doesn't mean that you won't get it, either.

Scientists have found that certain risk factors make a woman more likely to develop vaginal cancer. Even if a woman with vaginal cancer has one or more risk factors, it is impossible to know for sure how much that risk factor contributed to causing the cancer. And many women with vaginal cancer do not have any apparent risk factors.

Age

Squamous cell cancer of the vagina occurs mainly in older women. Only 15% of cases are found in women younger than 40. Almost half of cases occur in women who are 70 years old or older.

Diethylstilbestrol (DES)

DES is a hormonal drug that was given to some women to prevent miscarriage during the years between 1940 and 1971. Women whose mothers took DES (when pregnant with them) develop clear-cell adenocarcinoma of the vagina or cervix more often than would normally be expected. There is about 1 case of this type of cancer in every thousand women whose mother took DES during their pregnancy. This means that about 99.9% of "DES daughters" do not develop this cancer.

DES-related clear cell adenocarcinoma is more common in the vagina than the cervix. The risk appears to be greatest in those whose mothers took the drug during their first 16 weeks of pregnancy. The average age at diagnosis is 19 years. Since the use of DES during pregnancy was stopped by the FDA in 1971, even the youngest DES daughters are older than 35 - past the age of highest risk. But there is no age when a woman is safe from DES-related cancer. Doctors do not know exactly how long women remain at risk.

Although DES daughters have an increased risk of developing clear cell carcinomas, women don’t have to be exposed to DES for clear cell carcinoma to develop. In fact, cases of the disease were diagnosed before DES was invented.

Vaginal adenosis

Normally, the vagina is lined by flat cells called squamous cells. In about 40% of women who have already started periods, the vagina may contain one or more areas where it is lined instead by glandular cells. These cells look like those found in the glands of the cervix, or the lining the body of the uterus (endometrium), or the lining of the fallopian tubes. This change is called adenosis. It occurs in nearly all women who were exposed to DES during their mothers' pregnancy. Having adenosis increases the risk of developing clear cell carcinoma, but this cancer is still very rare. The risk of clear cell carcinoma in a woman who has adenosis that is not related to DES is very, very small. Still, many doctors feel that any woman with adenosis should have very careful screening and follow-up.

Human papillomavirus infection

Up to 90% of vaginal cancers and pre-cancers (vaginal intraepithelial neoplasia -- VAIN) contain the human papillomavirus (HPV). HPV is a group of more than 100 related viruses. They are called papilloma viruses because some of them cause a type of growth called a papilloma. Papillomas are not cancers and are more commonly known as warts. Different HPV types can cause different types of warts in different parts of the body. Some types cause common warts on the hands and feet. Other types tend to cause warts on the lips or tongue. Certain HPV types can infect the female and male genital organs and the anal area. HPV can be passed from one person to another during skin-to-skin contact. It can be spread during sex -- including vaginal intercourse, anal intercourse, and even during oral sex.

Certain types of HPV have been strongly associated with vaginal cancers. These types, HPV types 16 and 18, also cause cervical cancer. Different HPV types cause genital warts. Most cases of genital warts are caused by 2 HPV types: HPV 6 and HPV 11.

HPV infections occur mainly in young women and are less common in women over 30. The reason for this is not clear. Infection with HPV can be present for years without any symptoms, so the absence of visible warts cannot be used to tell if someone has HPV. Even when someone doesn't have warts (or any other symptom), he (or she) can still be infected with HPV and pass the virus to somebody else.

Condoms ("rubbers") do provide some protection against HPV, but they cannot completely protect against infection. This is because HPV can still be passed from one person to another by skin-to-skin contact with an HPV-infected area of the body that is not covered by a condom -- like the skin in the genital or anal area. Still, it is important to use condoms to protect against AIDS and other sexually transmitted illnesses that are passed on through some body fluids.

Certain types of sexual behavior increase a woman's risk of getting HPV infection. These include starting to have sex at an early age, having many sexual partners, having sex with a person who has had many partners, and having unprotected sex at any age.

Vaccines have been developed to help prevent infection with some types of HPV. Right now, there is an HPV vaccine that has been approved for use in the United States by the Food and Drug Administration (FDA). This vaccine is called Gardasil®, and it protects against HPV types 6, 11, 16, and 18. It also helps prevent cancers of the cervix, vulva, and vagina. More HPV vaccines are being developed and tested.

Cervical cancer

Having cervical cancer or pre-cancer (cervical intraepithelial neoplasia or cervical dysplasia) increases a woman's risk of vaginal squamous cell cancer. This is most likely because cervical and vaginal cancers have similar risk factors, such as HPV infection and smoking.

Some studies suggest that treating cervical cancer with radiation therapy may increase the risk of vaginal cancer, but this was not seen in other studies, and the issue remains unresolved.

Smoking

Smoking cigarettes more than doubles a woman's risk of getting vaginal cancer.

Alcohol

Alcohol intake may affect the risk of vaginal cancer. A study of alcoholic women found more cases of vaginal cancer than was expected. But this study was flawed because it didn't look at other factor that can alter risk, such as smoking and HPV infection. A more recent study that did take these other risk factors into account found a decreased risk of vaginal cancer in women who do not drink alcohol at all .

HIV infection

HIV (human immunodeficiency virus), the virus that causes AIDS, also increases the risk of vaginal cancer.

Vaginal irritation

In some women, stretching of the pelvic ligaments may cause the uterus to sag into the vagina or even extend outside the vagina. This condition is called uterine prolapse and can be treated by surgery or by wearing a pessary, a device to keep the uterus in place. Some studies suggest that long-term (chronic) irritation of the vagina in women using a pessary may slightly increase the risk of squamous cell vaginal cancer. But this association is extremely rare, and no studies have conclusively proven that pessaries actually cause vaginal cancer.

Last Medical Review: 12/30/2008
Last Revised: 09/14/2009