What causes vulvar cancer

Overview

Vulvar cancer is a rare type of cancer that forms on the outer surface of the female genitalia, known as the vulva. The vulva includes the labia (lips of the vagina), the clitoris, and the perineum. While it can affect women of all ages, it is most commonly diagnosed in women over the age of 65. Understanding the causes of vulvar cancer is crucial for prevention, early detection, and effective treatment.

What is Vulvar Cancer?

Vulvar cancer refers to malignancies that arise from the tissues of the vulva. The most common type is squamous cell carcinoma, which originates in the flat, thin cells (squamous cells) that line the surface of the vulva. Other less common types include melanoma, basal cell carcinoma, sarcoma, and adenocarcinoma. Early-stage vulvar cancer may present as a lump, sore, or skin change on the vulva that doesn't heal, often accompanied by itching or pain.

The Primary Culprit: Human Papillomavirus (HPV)

The overwhelming majority of vulvar cancers, particularly those occurring in younger women, are caused by persistent infection with certain high-risk strains of the Human Papillomavirus (HPV). HPV is a very common group of viruses, with over 200 types. Some types cause warts (genital or common warts), while others, known as high-risk types, can lead to cellular changes that may eventually develop into cancer.

The high-risk HPV types most frequently implicated in vulvar cancer are HPV 16 and HPV 18. These viruses infect the cells of the cervix, anus, penis, and vulva. In most cases, the immune system clears the HPV infection on its own. However, in a subset of individuals, the virus persists, and over years or decades, this persistent infection can lead to the development of pre-cancerous lesions, such as vulvar intraepithelial neoplasia (VIN), and subsequently invasive vulvar cancer.

It's important to note that not all HPV infections lead to cancer. Many are transient and asymptomatic. However, the persistent infection with high-risk HPV strains is a significant risk factor.

Other Contributing Factors

While HPV is the dominant cause, several other factors can increase a woman's risk of developing vulvar cancer:

Weakened Immune System

A compromised immune system makes it harder for the body to fight off HPV infections and eliminate abnormal cells. Conditions that weaken the immune system include:

• HIV infection: The human immunodeficiency virus (HIV) attacks the immune system, making individuals more susceptible to persistent HPV infections and the development of HPV-related cancers, including vulvar cancer.
• Immunosuppressant medications: Women who have undergone organ transplants and are taking medications to prevent their immune system from rejecting the new organ are at an increased risk. Similarly, long-term use of corticosteroids can also suppress the immune system.

Pre-cancerous Conditions (Vulvar Intraepithelial Neoplasia - VIN)

Vulvar intraepithelial neoplasia (VIN) is a pre-cancerous condition characterized by abnormal cell growth on the surface of the vulva. VIN is often caused by HPV infection. VIN is graded into different levels (VIN 1, VIN 2, VIN 3), with higher grades indicating more significant cellular abnormalities. If left untreated, VIN, especially VIN 2 and VIN 3, can progress to invasive vulvar cancer. Regular screening and prompt treatment of VIN are crucial for preventing cancer.

Chronic Inflammation and Irritation

Long-term inflammation and irritation of the vulvar skin can also play a role, particularly in cases not directly linked to HPV. Conditions that cause chronic vulvar inflammation include:

• Lichen sclerosus: This is a chronic inflammatory skin condition that causes thinning, whitening, and sometimes scarring of the vulvar skin. It can lead to itching, pain, and fissuring. While the exact cause of lichen sclerosus is not fully understood, it is believed to have an autoimmune component. Women with lichen sclerosus have a higher risk of developing vulvar cancer, especially if the condition is extensive or has been present for a long time.
• Other chronic dermatological conditions: Conditions like chronic eczema or psoriasis affecting the vulvar area, if severe and prolonged, might also contribute to an increased risk, though less commonly than lichen sclerosus.

Smoking

Cigarette smoking is a known risk factor for many cancers, and it also increases the risk of vulvar cancer. Smoking can weaken the immune system, making it harder to clear HPV infections, and it may also directly damage vulvar tissues. Women who smoke are more likely to develop vulvar cancer, and their cancers may be more aggressive.

Age

While vulvar cancer can occur at any age, the risk increases significantly with age. The majority of cases are diagnosed in women over 65. This may be due to a longer cumulative exposure to risk factors or a decline in immune function over time.

History of Other Genital Cancers

Women who have had cervical cancer or vaginal cancer, which are also often linked to HPV, may have an increased risk of developing vulvar cancer due to shared risk factors and potential for field cancerization (a phenomenon where a larger area of tissue is prone to developing cancer).

Prevention and Early Detection

Understanding these causes highlights the importance of preventive measures. HPV vaccination is highly effective in preventing infections with the most common high-risk HPV types that cause cancer. Regular gynecological check-ups and prompt attention to any persistent changes on the vulva, such as sores, lumps, itching, or pain, are essential for early detection.