Risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t.
Several factors can affect your risk of anal cancer. But having a risk factor, or even several risk factors, does not mean that you will get cancer. Many people with risk factors never develop anal cancer, while others with this disease may have few or no known risk factors.
Several factors have been found to increase the risk of anal cancer, including:
- Older age. Most cases of anal cancer occur in people age 50 and older.
- Many sexual partners. People who have many sexual partners over their lifetimes have a greater risk of anal cancer.
- Anal sex. People who engage in anal sex have an increased risk of anal cancer.
- Smoking. Smoking cigarettes may increase your risk of anal cancer.
- History of cancer. Those who have had cervical, vulvar or vaginal cancer have an increased risk of anal cancer.
- Human papillomavirus (HPV). HPV infection increases your risk of several cancers, including anal cancer and cervical cancer. HPV infection is a sexually transmitted infection that can also cause genital warts.
- Drugs or conditions that suppress your immune system. People who take drugs to suppress their immune systems (immunosuppressive drugs), including people who have received organ transplants, may have an increased risk of anal cancer. HIV — the virus that causes AIDS — suppresses the immune system and increases the risk of anal cancer.
Anal cancer rarely spreads (metastasizes) to distant parts of the body. Only a small percentage of tumors are found to have spread, but those that do are especially difficult to treat. Anal cancer that metastasizes most commonly spreads to the liver and the lungs.
Anal cancer may be detected during a routine digital rectal exam or during a minor procedure, such as removal of what is believed to be a hemorrhoid. Tests and procedures used to diagnose anal cancer include:
Physical examination: Examining your anal canal and rectum for abnormalities. During a digital rectal exam, your doctor inserts a gloved, lubricated finger into your rectum. He or she feels for anything unusual, such as growths.
Visually inspecting your anal canal and rectum. Your doctor may use a short, lighted tube (anoscope) to inspect your anal canal and rectum for anything unusual.
Imaging: Taking sound wave pictures (ultrasound) of your anal canal. To create a picture of your anal canal, your doctor inserts a probe, similar to a thick thermometer, into your anal canal and rectum. The probe emits high-energy sound waves, called ultrasound waves, which bounce off tissues and organs in your body to create a picture. Your doctor evaluates the picture to look for anything abnormal.
Biopsy: Removing a sample of tissue for laboratory testing. If your doctor discovers any unusual areas, he or she may take small samples of affected tissue (biopsy) and send the samples to a laboratory for analysis. By looking at the cells under a microscope, doctors can determine whether the cells are cancerous.