HPV, also known as the human papillomavirus, is a common sexually transmitted infection that can cause warts to appear in the anogenital region. In addition to causing genital warts, some types of HPV infection are associated with an increased risk of developing certain kinds of cancer, including cancer of the anus.
HPV and Cancer
Of the more than 100 strains of HPV, some of them are termed "high-risk," because they are associated with the development of cervical and anal cancer, the American Cancer Society explains. These strains of the virus, upon entering a cell, can cause genetic changes that predispose cells to becoming cancerous. The American Cancer Society notes that 80 percent of all cases of squamous cell cancer of the anus can be linked to an infection from HPV-16 or HPV-18.
Incidence
HPV causes approximately 2,500 cases of anal cancer each year in the United States, the Centers for Disease Control and Prevention (CDC) notes. Of these, 1,600 will be in women, with the majority of the cases occurring in white women. Black males make up the majority of the remaining 900 cases that will occur in men. HPV-associated anal cancer is more common among people who engage in anal sex; although, people who do not report any anal intercourse may also develop anal HPV.
Other Risk Factors
There are a number of other factors that can predispose a person to developing anal cancer, the American Society of Colon and Rectal Surgeons (ASCRS) explains. Patients who are over the age of 50 or who smoke are more likely to develop anal cancer. People who are infected with HIV or otherwise have weakened immune systems are also prone to anal cancer. Anal cancer is associated with chronic irritation of the anus, as well as previous exposure of the pelvis to radiation.
Diagnosis
Doctors can perform an anal pap smear, according to TheBody.com, to screen patients for cellular changes associated with anal cancer. This test allows a physician to swab the anal region to get a sample of the cells in the anus. A medical professional then examines these cells under a microscope to see if they have become cancerous or if any dysplasia is present. Dysplasia describes cells that have developed abnormalities, which predispose them to becoming cancerous.
Treatment
There are three main ways to treat anal cancer, the ASCRS explains. Surgery, which is performed in an attempt to remove as much of the cancerous tissue as possible, is often the first-line treatment approach. After surgery, patients may receive radiation therapy, chemotherapy or both. Radiation treatment uses high-energy X-rays to damage the cancerous cells, whereas chemotherapy uses medications that poison cancer cells.
