The specific cause of anal cancer is not known. Anal cancer only represents only 1% of all reported cancer cases. In 2009, there were 5,290 new cases of anal cancer and approximately 790 annual deaths from anal cancer. Research on anal cancer is done less than other cancers but there are a few known risk factors associated with anal cancer.

Human Papilloma Virus (HPV)

Having this virus is associated with anal cancer because the type of tissue found inside the anus is squamous cell. Cancer of the squamous is known to be caused by HPV. There are many subtypes of human papilloma virus out there and the ones that are most closely associated with anal cancer are HPV-16. HPV-16, as well as HPV-18, HPV-31, HPV-33, and HPV-45. Collectively, these subtypes of HPV are known as the high risk human papilloma viruses. HPV is classified as a sexually transmitted infection and are known to cause genital warts. However, most people with HPV do not have genital warts as a symptom.

HIV infection

People who have human immunodeficiency virus, the virus that causes AIDS, are known to be at a much higher risk of getting anal cancer. Drug treatments of HIV have helped reduce the occurrence of many HIV related disease but they have not affected the cancer rates in these patients.

Sex

An increased risk of anal cancer has been reported in those who have multiple partners and also have unprotected sex. This also increases the chances of getting both HPV and HIV. Receptive anal intercourse has also been linked to anal cancer in both men and women. People younger than 30 years old are at a greater risk.

Smoking

The deadly cocktail of harmful chemicals found in tobacco smoke enters through the blood stream and affects the entire body. Current smokers are at a greater risk of getting anal cancer. Quitting can help reduce this risk.

Compromised Immune system

People who have a compromised immune system includes people with HIV, AIDS, and people who have had organ transplants. Also, some drugs suppress the immune system as a side effect. All of these people have a greater risk of getting anal cancer.

Chronic anal inflammation

Those who have chronic open sores on the anus or inflammation of the anus are at an increased risk of getting cancer of the anus.

Pelvic Radiation

People who have undergone extensive radiation in the pelvic region are at a significant risk of getting anal cancer.