Causes of Vulvar Cancer

Vulvar cancer is a rare form of cancer affecting the vulva and the external genital organs in women. It accounts for less than 1% of all cancer cases in the UK.

Who does vulvar cancer affect?

The cancer rarely affects the young and most commonly affects women over 65.

How common is vulvar cancer?

The lifetime risk in the UK is 1 in 316 women.

In the United States, vulvar cancer accounts for about 4% of cancers of the female reproductive organs and 0.6% of all cancers in women. In the US, women have a 1 in 406 chance of developing vulvar cancer during their lifetime. (1-5)

Types of vulvar cancer

Most vulvar cancers are of squamous cell carcinoma type – around 75 to 85%. The rest are of various other types like melanoma, adenocarcinoma etc.

In half of the cases the labia majora – the external lips of the vulva is affected. The inner lips or labia minora is affected in nearly 205 cases. In small number of cases the glands and the clitoris is affected.

How does vulvar cancer begin?

Cancer starts when the blue print within the cells called the DNA and genes are altered. This leads to uncontrolled multiplication of the affected cells till they invade surrounding cells.

How does vulvar cancer spread?

Vulvar cancer spreads in three major ways. It spreads out of the vulvar tissue into surrounding parts of the body like the urethral opening and the vagina.

It may also spread via the lymphatic channels and lymph nodes to affect the whole body. The first lymph nodes that are invaded are the nearest ones in the groin.

The cancer may also spread via blood vessels to large organs like liver, lungs and brain. Cancer that has spread to other parts of the body is known as metastatic cancer.

Risk factors for vulvar cancer

Exact cause of vulvar cancer is unknown. However some risk factors may play a role in this cancer. Risk factors of vulvar cancer include:

• Advancing age - Two thirds of the cases of vulvar cancer are seen in women over 65 and half of the cases in women over 75.
• Long term infection with human papilloma virus (HPV) - Specific strains such as HPV 16 are responsible for cervical cancer. They are also implicated in vulvar cancer.  The HPV virus is spread during unprotected sexual intercourse, including anal and oral sex.
• Vulvar intraepithelial neoplasia (VIN) - This is a pre-cancerous condition where the cells are altered in their function and appearance but not yet cancerous. There may be symptoms like itchiness, burning sensation on urination and raised red or white patches of skin.  VIN may be of two types - usual VIN or undifferentiated VIN seen in women between 35 and 55. It is due to HPV infection. Differentiated VIN or dVIN is a rare type seen in women between 55 and 85. It is associated with skin conditions of the vulva. VIN is treated using a cream called Imiquimod that kills abnormal cells.
• Non-cancerous skin conditions of the vulva - Women who have non-cancerous skin conditions of the vulva like lichen sclerosis are at an increased risk of vulvar cancer. Around 1 in 50 women with these skin lesions go on to develop vulvar cancer.

Other risk factors for vulvar cancer

Other risk factors associated with vulvar cancer include:

• Smoking
• Those infected with human immunodeficiency virus (HIV) are also at a raised risk of HPV infection and in turn raises risk of vulvar cancer.
• Those with abnormal looking moles or lesions in their vulva are at a higher risk of the mole turning to vulvar cancers like melanoma.
• Other sexually transmitted disease, having multiple sexual partners, never having had children etc. are other risk factors of vulvar cancer.

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