A risk factor is anything that changes 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 many cancers. But risk factors don't tell us everything. Cancers often occur in patients without risk factors. Also, having a risk factor, or even several, doesn't mean that you will get the disease.

Although several risk factors increase the odds of developing vulvar cancer, 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, it is usually not possible to say with certainty that a particular risk factor was the cause.

Age

The risk of vulvar cancer goes up with age. Less than 20% of cases are in women younger than age 50, and more than half occur in women over age 70. The average age of women diagnosed with invasive vulvar cancer is 70, whereas women diagnosed with non-invasive vulvar cancer average about 20 years younger.

Human papilloma virus

Human papilloma virus (HPV) is a group of more than 100 types of 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 called warts. HPV can be passed from one person to another during skin-to-skin contact. One way that HPV can be spread is through sex - including vaginal intercourse, anal intercourse, and even during oral sex.

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. HPV infection is thought to be responsible for up to half of vulvar cancers overall, and most of the cases that occur in younger women.

Certain HPV types can infect the outer female and male genital organs and the anal area, causing raised, bumpy warts. These warts may be barely visible or they may be several inches across. The medical term for genital warts is condyloma acuminatum. 2 types of HPV, HPV 6 and HPV 11, cause most cases of genital warts. These 2 types are seldom linked to cancer, and so are called "low-risk" types of HPV. However, other HPV types have been linked with genital cancer and so are known as "high-risk" types of HPV. These include HPV 16, HPV 18, HPV 31, as well as others. Infection with a high-risk HPV may produce 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 older women HPV is less likely a risk factor. Some doctors think there are 2 kinds of vulvar cancer. One 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 who are infected with a high risk HPV have a much higher risk of developing vulvar cancer if they smoke.

Human immunodeficiency virus

Human immunodeficiency virus (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. This may, in turn, increase the risk of vulvar pre-cancer and cancer. Scientists also believe that the immune system plays a role in destroying cancer cells and slowing their growth and spread.

Vulvar intraepithelial neoplasia

Squamous cell carcinoma of the vulva usually forms slowly over many years. Often, it is preceded by pre-cancerous changes that may last for several years. The medical term most often used for this pre-cancerous condition is vulvar intraepithelial neoplasia (VIN). "Intraepithelial" means that the abnormal cells are only found in the surface layer of the vulvar skin (epithelium). VIN is often divided into 3 categories -- VIN1, VIN2, and VIN3, with higher numbers indicating furthest progression toward a true cancer. Most cases of VIN are caused by HPV infection.

In the past, the term dysplasia had been used instead of VIN. This term is used much less now. When talking about dysplasia, there is also a range of increasing progress toward cancer -- first, mild dysplasia; next, moderate dysplasia; then severe dysplasia; and, finally, carcinoma in situ.

Although women with VIN have an increased risk of developing invasive vulvar cancer, most cases of VIN never progress to cancer. Still, since it is not possible to tell which cases will become cancers, treatment or close medical follow-up is needed.

In the past, cases of VIN were included under the broad category of disorders known as vulvar dystrophy. Since this category included a wide variety of other diseases, most of which are not pre-cancerous, most doctors no longer use this term.

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 having LSA later developing vulvar cancer.

Other genital cancers

Women with cervical cancer also have a higher risk of vulvar cancer. This is likely because these cancers share certain risk factors. The same HPV types that are linked to cervical cancer are also linked to vulvar cancer. Smoking is also linked to a higher risk of both cervical and vulvar cancers.

Melanoma or atypical moles

Women who have had melanoma or dysplastic nevi (atypical moles) elsewhere on the body have an increased risk of developing a melanoma on the vulva. A family history of melanoma also leads to an increased risk.

Last Medical Review: 12/30/2008
Last Revised: 05/14/2009