Although uncommon, anal cancer is preventable with the human papillomavirus (HPV) vaccine and other lifestyle modifications, according to a review in CMAJ on the screening and prevention of this cancer (Canadian Medical Association Journal).
Currently, no Canadian screening guideline exists for anal cancer, although screening is recommended in Europe and the United States.
Evidence indicates that people at high risk of anal cancer, such as those with HIV, women with genital cancers or precancerous lesions and people who have undergone organ transplants, should be screened for anal cancer. Anal cancer affects more women than men, with about 64% (385) of cases in Canada found in women. Screening may involve an anal Pap test or exploration of the anal canal (high-resolution anoscopy).
"Anal cancer is a hidden cancer that is not talked about publicly," states Dr. Irving Salit, Division of Infectious Diseases, University Health Network and the University of Toronto, Toronto, Ontario. "In certain at-risk populations (HIV + MSM [men who have sex with men], women with genital cancers) anal cancer is very common - much more common than colon cancer or cervical cancer. It is the commonest cancer seen in HIV. Screening tests are available for anal pre-cancers but are not promoted or funded by our provincial governments."
Because about 80% - 90% of anal cancers are caused by HPV, the HPV vaccine is effective prevention. Condom use and smoking cessation (smoking is a risk factor for the disease) can also help reduce the risk of anal cancer.
"In addition to its role in preventing cervical cancer among women, the quadrivalent HPV vaccine is recommended in Canada for boys and men between the ages of 9 and 26 years for the prevention of AIN [anal intraepithelial neoplasia] grades 1-3, anal cancer and anogenital warts."
Family doctors should be aware of the warning signs for anal cancer and should perform digital anal exams on people at high risk.
"Anal cancer is a preventable sexually transmitted disease. It is important to recognize populations at risk and counsel patients on early detection, safer sex practices, smoking cessation and HPV vaccination," conclude the authors.