This is a medical question of type : prevention 
 How to prevent Anal Cancer ? 
 Key Points
                    - Avoiding risk factors and increasing protective factors may help prevent cancer.    - The following are risk factors for anal cancer:         - Anal HPV infection     - Certain medical conditions             - History of cervical, vaginal, or vulvar cancer       - HIV infection/AIDS       - Immunosuppression           -  Certain sexual practices     - Cigarette smoking        - The following protective factor decreases the risk of anal cancer:         - HPV vaccine        -  It is not clear if the following protective factor decreases the risk of anal cancer:         - Condom use        - Cancer prevention clinical trials are used to study ways to prevent cancer.    -  New ways to prevent anal cancer are being studied in clinical trials.
                
                
                    Avoiding risk factors and increasing protective factors may help prevent cancer.
                    Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
                
                
                    The following are risk factors for anal cancer:
                    Anal HPV infection    Being infected with human papillomavirus (HPV) is the main risk factor for anal cancer. Being infected with HPV can lead to squamous cell carcinoma of the anus, the most common type of anal cancer. About nine out of every ten cases of anal cancer are found in patients with anal HPV infection.     Patients with healthy immune systems are usually able to fight HPV infections. Patients with weakened immune systems who are infected with HPV have a higher risk of anal cancer.       Certain medical conditions       History of cervical, vaginal, or vulvar cancer      Cervical cancer, vaginal cancer, and vulvar cancer are related to HPV infection. Women who have had cervical, vaginal, or vulvar cancer have a higher risk of anal cancer.          HIV infection/AIDS     Being infected with human immunodeficiency virus (HIV) is a strong risk factor for anal cancer. HIV is the cause of acquired immunodeficiency syndrome (AIDS). HIV weakens the body's immune system and its ability to fight infection. HPV infection of the anus is common among patients who are HIV-positive.      The risk of anal cancer is higher in men who are HIV-positive and have sex with men compared with men who are HIV-negative and have sex with men. Women who are HIV-positive also have an increased risk of anal cancer compared with women who are HIV-negative.     Studies show that intravenous drug use or cigarette smoking may further increase the risk of anal cancer in patients who are HIV-positive.          Immunosuppression      Immunosuppression is a condition that weakens the body's immune system and its ability to fight infections and other diseases. Chronic (long-term) immunosuppression may increase the risk of anal cancer because it lowers the body's ability to fight HPV infection.     Patients who have an organ transplant and receive immunosuppressive medicine to prevent organ rejection have an increased risk of anal cancer.     Having an autoimmune disorder such as Crohn disease or psoriasis may increase the risk of anal cancer. It is not clear if the increased risk is due to the autoimmune condition, the treatment for the condition, or a combination of both.           Certain sexual practices    The following sexual practices increase the risk of anal cancer because they increase the chance of being infected with HPV:            - Having receptive anal intercourse (anal sex).     - Having many sexual partners.     - Sex between men.           Men and women who have a history of anal warts or other sexually transmitted diseases also have an increased risk of anal cancer.       Cigarette smoking    Studies show that cigarette smoking increases the risk of anal cancer. Studies also show that current smokers have a higher risk of anal cancer than smokers who have quit or people who have never smoked.
                
                
                    The following protective factor decreases the risk of anal cancer:
                    HPV vaccine        The human papillomavirus (HPV) vaccine is used to prevent anal cancer, cervical cancer, vulvar cancer, and vaginal cancer caused by HPV. It is also used to prevent lesions caused by HPV that may become cancer in the future.     Studies show that being vaccinated against HPV lowers the risk of anal cancer. The vaccine may work best when it is given before a person is exposed to HPV.
                
                
                    It is not clear if the following protective factor decreases the risk of anal cancer:
                    Condom use    It is not known if the use of condoms protects against anal HPV infection. This is because not enough studies have been done to prove this.
                
                
                    Cancer prevention clinical trials are used to study ways to prevent cancer.
                    Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.    The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.
                
                
                    New ways to prevent anal cancer are being studied in clinical trials.
                    Clinical trials are taking place in many parts of the country. Information about clinical trials for anal cancer prevention can be found in the Clinical Trials section of the NCI Web site.