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.

Several risk factors increase the odds of developing vulvar cancer, although most women with these risks do not develop it. And some women without any apparent risk factors develop vulvar cancer. When a woman develops vulvar cancer or pre-cancerous changes, it is usually not possible to say with certainty that a particular risk factor was the cause.

Age: Almost 85% of women with vulvar cancer are over age 50, and half are over age 70 at the time their cancer is first diagnosed. However, 15% of new patients are under age 40. The average age of women diagnosed with invasive cancer is 70, whereas women diagnosed with non-invasive vulvar cancer average about 20 years younger.

Human papillomavirus (HPV) infection: HPV infection is thought to be responsible for most of the vulvar cancers in younger women. HPVs are a group of more than 100 types of viruses that are called papillomaviruses because they can cause papillomas or warts. Different HPVs 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. Sexual contact at a young age increases the likelihood of HPV infection. Having a large number of sexual partners or having sex with persons who have had many sexual partners increases the risk of exposure to HPV.

When HPVs infect the skin of the external (outer) genital organs and anal area (around the opening of the intestinal tract), they often cause raised, bumpy warts. These may be barely visible, or they may be several inches across. The medical term for genital warts is condyloma acuminatum.

Most genital warts are caused by 2 HPV types, HPV 6 and HPV 11. These rarely develop into cancer and are called "low-risk" viruses. However, other sexually transmitted HPVs have been linked with genital or anal cancers in both men and women. These are considered "high-risk" types of HPV and include HPV 16, HPV 18, HPV 31, as well as some others. Infection with high-risk HPVs often produces no visible signs until pre-cancerous changes or cancer develops. In general, vulvar cancer in younger women tends to be associated with infection with the high-risk HPV types. In elderly women HPV is less likely a risk factor.

In elderly women HPV is less likely a risk factor. Some doctors think there are two kinds of vulvar cancer. One kind is associated with HPV infection and tends to occur in younger women. The other kind is not associated with HPV infection, and more often is found in older women.

Smoking: Smoking exposes the body to many cancer-causing chemicals that affect more than the lungs. These harmful substances can be absorbed into the lining of the lungs and spread throughout the body. Among women who have a history of genital warts, smoking further increases the risk of developing vulvar cancer. Women are infected with a high risk HPV have a much higher risk of developing vulvar cancer if they smoke.

Human immunodeficiency virus (HIV) infection: HIV is the virus that causes the acquired immunodeficiency syndrome (AIDS). Because this virus damages the body's immune system, it makes women more susceptible to persistent HPV infections, which may, in turn, increase the risk of pre-cancerous vulvar changes and vulvar cancer. Scientists also believe that the immune system plays a role in destroying cancer cells and slowing their growth and spread.

Vulvar intraepithelial neoplasia (VIN): Women with VIN have an increased risk of developing invasive vulvar cancer. Although most cases of VIN never progress to cancer, it is not possible to tell which will, so treatment or close medical follow-up is needed.

Lichen sclerosus: This disorder, also called lichen sclerosus et atrophicus (LSA), causes the vulvar skin to become very thin and itchy. The risk of vulvar cancer appears to be slightly increased by LSA, with about 4% of women with LSA later developing vulvar cancer.

Other genital cancers: Women with vulvar cancer also have a higher risk of cervical cancer. The likely reason for this association is the role of HPV infection in causing both of these cancers. Smoking is associated with an increased risk of cervical cancer. Because of the smoking, women also have a higher risk of other smoking-related cancers.

Melanoma or atypical moles on nonvulvar skin: Women with a family history of melanoma or dysplastic nevi (atypical moles) elsewhere on the body are at risk for developing a melanoma on the vulva. Last Revised: 06/21/2006