A risk factor is anything that increases a person's 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 cancers of the lung, mouth, larynx, bladder, kidney, and several other organs. But having a risk factor, or even several, does not mean that a person will get the disease.

Scientists have found that certain risk factors make a woman more likely to develop vaginal cancer. Even if a woman does have one or more risk factors for vaginal cancer, 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.. Over two-thirds of women are 60 years old or older when they are diagnosed.

Diethylstilbestrol (DES): DES is a hormonal drug that was prescribed between 1940 to 1971 for some women thought to be at increased risk for miscarriages. About 1 out of every 1,000 women whose mothers took DES when pregnant with them develop clear cell adenocarcinoma of the vagina or cervix. Clear cell adenocarcinomas are more common in the vagina than the cervix. Stated another way, about 99.9% of "DES daughters" do not develop this cancer. 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.

Most DES daughters are now between 30 and 60 years old, so the number of new cases of cervical and vaginal DES-related clear cell adenocarcinoma has been decreasing during the past 2 decades. However, this type of cancer has been found recently in a woman in her early 40s, and doctors still do not know exactly how long women remain at risk for DES-related cancers.

Although DES daughters have an increased risk of developing clear cell carcinomas, about 40% of women with this cancer have no known exposure to DES or related medications. Some of these patientsÂ’ mothers might have taken DES but they did not recall the name of the drug. It is certain, however, that DES exposure is not needed for formation of clear cell carcinoma since some 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 the vagina is lined instead by cells that resemble those found in glands of the lower uterus (endocervix) or upper uterine lining (endometrium). This change is called adenosis. It occurs in nearly all women exposed to DES during fetal development. Although having adenosis increases the risk of developing clear cell carcinoma, this cancer is extremely rare. The risk of a woman with adenosis not exposed to DES developing clear cell carcinoma is very, very small. Nonetheless, many doctors recommend especially careful screening for these women.

Human papillomavirus (HPV) infection: About 65% to 80% of VAIN or vaginal cancers contain the HPV virus. HPVs are a group of more than 100 types of viruses called papilloma viruses because they can cause papillomas (warts). Different HPV types 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. These HPV types are passed from one person to another during sexual contact.

Certain types of HPV have been strongly associated with vaginal cancers. These types, namely types 16 and 18, are also associated with cervical cancer. These are different than the types that cause genital warts. Certain types of sexual behavior increase a woman's risk of getting HPV infection. These high-risk sexual behaviors include intercourse 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.

Cervical cancer: Having cervical cancer or cervical pre-cancerous conditions (cervical intraepithelial neoplasia or cervical dysplasia) increases a woman's risk of developing vaginal squamous cell cancer. This is because cervical and vaginal cancers have similar risk factors, such as HPV infection. In fact, a recent study found that in women who had a vaginal cancer after treatment for cervical cancer, the DNA changes in the vaginal cancer cells were the same as those in the previous cervical cancer cells. The reason for this isn’t known.

Some studies suggest that women whose cervical cancers were treated with radiation therapy have an increased risk of vaginal cancer, possibly because the radiation damaged the DNA of vaginal cells. However, other studies have not supported this conclusion, and the issue remains unresolved.

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, called uterine prolapse, 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. However, this association is extremely rare, and no studies have conclusively proven that pessaries actually cause vaginal cancer.

Smoking: Tobacco use may also play a role in this disease, particularly in younger women, as it does for cervical cancer. One clue is that women with vaginal cancer have a high chance of developing lung cancer, and lung cancer is very closely related to smoking.

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

Revised: 07/21/2006