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Several risk factors for cancer of the vulva have been
identified, and we are beginning to understand how these factors can
cause cells in the vulva to become cancerous.
Researchers have made great progress in understanding how
certain changes in DNA can cause normal cells to become cancerous. DNA
is the chemical that carries the instructions for nearly everything our
cells do. We usually look like our parents because they are the source
of our DNA. However, DNA affects more than our outward appearance. Some
genes (parts of our DNA) contain instructions for controlling when our
cells grow and divide.
Certain genes that promote cell division are called oncogenes.
Others that slow down cell division or cause cells to die at the right
time are called tumor suppressor genes. Cancers can be caused by DNA
mutations (defects) that turn on oncogenes or turn off tumor suppressor
genes. Usually DNA mutations related to cancers of the vulva occur
during life rather than having been inherited before birth. Acquired
mutations may result from cancer-causing chemicals in tobacco smoke.
Sometimes they occur for no apparent reason.
Studies suggest that squamous cell cancer of the vulva (the
most common type) can develop in at least 2 ways. In up to half of
cases, human papilloma virus (HPV) infection appears to have an
important role. Vulvar cancers associated with HPV infection seem to
have certain distinctive features. They are often found along with
several other areas of vulvar intraepithelial neoplasia (VIN). The
women with these cancers tend to be younger and are often smokers.
The second process by which vulvar cancers develop does not
involve HPV infection. Vulvar cancers not linked to HPV infection
usually are diagnosed in older women (over age 55). These women often
have lichen sclerosis but rarely have VIN. DNA tests from vulvar
cancers in older women rarely show HPV infection, but often show
mutations of the p53 tumor suppressor gene. The p53 gene is important
in preventing cells from becoming cancerous. When this gene has
undergone mutation, it is easier for cancer to develop. Younger vulvar
cancer patients with HPV infection rarely have p53 mutations.
These discoveries have not yet affected treatment. But, they
may help in finding ways to prevent cancer of the vulva and at some
point may lead to changes in treatment.
Because vulvar melanomas and adenocarcinomas are so rare, much
less is known about how they develop.
Last Medical Review: 12/30/2008
Last Revised: 05/14/2009
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