When cancer cells form into benign or malignant tumors in the tissues of the anus, anal cancer has occurred. The anus is the opening at the bottom of your intestines where stool exits the body. Anal cancer is rare, but when it occurs, it may spread to other parts of the body. Some noncancerous forms of anal cancer can also turn cancerous over time.
Anal cancer risk factors
Anal Cancer: Symptoms, Causes, Treatments
Most anal cancers seem to be linked to infection with HPV the human papillomavirus. While HPV infection seems to be important in the development of anal cancer, the vast majority of people with HPV infections do not get anal cancer. A great deal of research is now being done to learn how HPV might cause anal cancer. There is good evidence that HPV causes many anal squamous cell carcinomas. But the role of this virus in causing anal adenocarcinomas is less certain.
Researchers continue to investigate the causes of anal cancer. Known risk factors that have been identified include chronic infection with high-risk types of human papillomavirus HPV , gender and age. HPV, a collection of more than viruses spread primarily by contact during vaginal, oral or anal sexual activity, is responsible for the majority of anal cancers. HPV may be asymptomatic for years, and persistent HPV infections may cause cell changes that, left untreated, may become cancer. The HPV vaccine provides protection against numerous strains of the virus, including subtypes 16 and 18, which are responsible for most HPV-related cancers.
Anal cancer occurs in the anus, which is at the end of the gastrointestinal tract. It is different from and less common than colorectal cancer, which is cancer of the colon or rectum. Anal cancer is rare, but the number of new cases is rising.