In the general population, anal cancer is a rare disease. Few people knew about it before Farrah Fawcett made public her struggle with the illness. Among men who have sex with men (MSM), and especially HIV-positive MSM, the incidence of anal cancer is significantly more prevalent and increasing annually.1 However, the majority of gay and bisexual men know little about the disease, have never been tested for it, nor know that screening tests exit. Health care professionals, too, remain divided on how and whether to screen for it. In fact, a standardized screening protocol for anal cancer does not yet exist.
Each year anal cancer is diagnosed in about two people out of every 100,000 people in the general population. HIV negative MSM are 20 times more likely to be diagnosed with anal cancer. Their rate is about 40 cases per 100,000. HIV-positive MSM are up to 40 times more likely to be diagnosed with the disease, resulting in a rate of 80 anal cancer cases per 100,000 people.
Anal cancer is caused by the same strains of Human Papilloma Virus (HPV) that cause cervical cancer in women. HPV is the most common sexually transmitted infection.2 There are over 100 different types of HPV, although only several strains are believed to increase the risk of cancer. Approximately 75% of all sexually active adults acquire HPV, often within the course of early adulthood and without any symptoms.3 Among MSM, it is transmitted through both protected and unprotected anal intercourse, and through skin-to-skin contact. Among heterosexual women, the vast majority of infections are cleared naturally by the body within a few years, usually by age 30. This appears to be less true for MSM, where the infections are often still present in later adulthood.2
Anal HPV is present in approximately 65% of HIV negative MSM and 95% of MSM who are HIV positive. Although HAART (highly active antiretroviral therapy) has decreased overall mortality from HIV, it has not reduced the incidence of anal squamous cell carcinoma (SCC).4 And, since it is spread through sexual skin-to-skin contact, condom use only partially reduces the risk of transmission. Other factors that increase the risk of anal cancer include a high number of sex partners, and use of alcohol, drugs and tobacco. Although many men have no obvious symptoms, one of the most common manifestations of HPV infection is genital warts which can affect the anus, the penis and/or the peritoneum, a large membrane in the abdominal cavity that connects and supports internal organs. Other possible symptoms are abnormal discharge from the anus, bleeding from the rectum and anus, anal itching, pain or pressure around the anus, and anal sores that do not heal.5
Cancer of the anus, like that of the cervix, develops slowly, beginning with minor cell changes. For women, a simple pap smear is used to detect these cell changes in the cervix in their early stages. With regular screening and proper treatment, cervical cancer can be prevented. In fact, since cervical pap smears have become a routine part of women's health care, cervical cancer rates have dropped dramatically, from rates that once resembled HIV-positive MSM anal cancer rates (80 per 100,000) to the current rate of approximately two per 100,000.
The anus and the cervix are biologically similar and both are target chambers for HPV infection.1,2 The same screening methodology (pap smear) can be used to test the anus for cancer and pre-cancerous cell changes. A growing number of gay physicians and health activists now believe that routine screening, using an anal pap smear, could reduce the incidence of anal cancer as dramatically as it has cervical cancer in women. They recommend that all MSM, especially those who are HIV-positive, be tested every one to three years, depending on their immunological well-being and CD4 count. For an HIV-positive gay man with a CD4 of over 500, it is recommended to repeat the test every 2 years. For an HIV-positive individual with a CD4 of fewer than 500, the recommendation is to repeat the test once a year. They suggest that HIV-negative individuals be tested every three years. Still, there are some clinicians who are not convinced that routine screening of all MSM is warranted. They cite the small number of positive cases, the shortage of facilities for follow-up procedures, and the fear, cost and pain involved in pursuing small cell changes, called dysplasias. In addition, most health insurance policies do not cover anal pap smears.
Recently, the relationship between HPV, anal cancer and HIV has received more research and media attention. The direct link between cervical cancer and HPV has been known for some time, and gynecologists typically perform a simple HPV test along with the cervical pap smear. That test is not able to categorize the exact strain of HPV that women carry. The FDA recently approved a new DNA test that identifies the two HPV strains (types 16, 18) responsible for most cervical cancers. At the moment, the new DNA test, called Cervista HPV 16/18, is not available in doctors' offices, but should start arriving within the next few months. In MSM, a clear relationship has not yet been determined between a high DNA HPV load and the cell changes that lead to anal cancer, but if confirmed, this test will become more widely used in the future. Then, only those with dangerous strains of HPV would require regular follow up screening with an anal pap smear.
Current research from the Fred Hutchison Cancer Research Center in Seattle, WA has found that, not only does HIV infection increase the risk of HPV infection, but that the converse is also true: HPV enhances susceptibility to HIV infection.6 This occurs because anal HPV lesions make the surface tissue of the anus thinner and more vulnerable to entry of the HIV virus. In addition, the immune cells activated by HPV infection are precisely the ones more vulnerable to HIV infection. These data underscore the value of HPV screening for all MSM.
The best form of prevention for anal cancer may be a vaccination against HPV infection. Currently, Gardasil by Merck has been approved as a prophylaxis against HPV and cervical cancer for girls between the ages of nine and 26. The Food and Drug Administration (FDA) is considering its use in boys, ages nine to 26 also, based on preliminary research showing that it was effective for them as well. The large study included 500 self-identified gay men. While that will prevent boys from developing anal cancer later in their lives, it is unclear how Gardasil may help adult MSM over 26 years old, HIV-positive men and those already infected with HPV. Gardasil and its competitor, Cervarix, by GlaxoSmithKline, are both expensive, between $360 and $500 for the three injections required. It is unclear if they will be covered by health insurance for adults who choose to be vaccinated.
There are some practitioners advocating Gardasil for use in MSM who have already been infected with HIV and/or HPV. This would be considered an "off label" use. The National Institutes of Health is conducting a clinical trial to see what benefits Gardasil might have for HIV-positive people. A number of men, both HIV-positive and negative, have opted to get vaccinated despite the fact Gardasil is not yet FDA-approved for use in men. This is considered an "off-label use" of the vaccine.7
Anal cancer is an increasing health threat to MSM, especially those who are HIV-positive, and there is no professional consensus about whether to vaccinate against it, screen for cell changes, or how to treat positive results on an anal pap smear. More research is needed and both the consumer and provider communities need to be educated.
It is critical that MSM talk to their medical providers about their sexual orientation, HIV status and sexual practices. The New York City Department of Health and Mental Hygiene found that nearly 40% of MSM do not come out to their provider.8 Those who are open about their sexual orientation often do not know enough about anal cancer to request a screening. The gay community must be educated, both HIV negative and HIV positive MSM, about HPV, anal cancer risk factors and the options available for screening and treatment. Then individuals can make informed decisions about whether to be screened and seek out a provider who is familiar with the options.
Liz Margolies, L.C.S.W., is Executive Director of the National LGBT Cancer Network. Bill Goeren, L.C.S.W., is the Senior Clinical Supervisor at CancerCare. To view references, go to www.gmhc.org/ti.html.
Palefsky, J. et al. "Update on HPV: Beyond Cervical Cancer." Sexuality, Reproduction and Menopause, Webcast from the ASRM Annual Meeting. www.srm-ejournal.com/srm.asp?id=7284. Accessed June 24, 2009.
Bratcher, J.et al. "Anogenital Human Papillomavirus Coinfection and Associated Neoplasia in HIV-Positive Men and Women" The PRN Notebook 13. (2008.)
Koutsky L. et al. "Epidemiology of Genital Human Papillomavirus. Infection." Epidemiologic Reviews 10(1), 122-163. (1988.)
Goldstone, S. et. al., "Hybrind Capture II Detection of Oncogenic Human Papillomavirus: A Useful Tool When Evaluating Men Who Have Sex with Men with Atypical Squamous Cells of Undetermined Significance on Anal Cytology" Disease of the Colon and Rectum 51(7), 1130-1136. (2008.)
Cichock, Mark, RN, "The Dangers of Anal Cancer -- The Silent Killer in Men with HIV" University of Michigan HIV/AIDS Treatment Program, Dec, 2008.
Fred Hutchinson Cancer Research Center. "Cancer-causing virus may increase HIV infection." http://fhcrc.org/about/pubs/center_news/online/2009/05/HIV_study.html. Accessed June 24, 2009.
The Body. "Ask the experts about Fatigue and Anemia -- Gay Men access to Gardasil?" www.thebody.com/Forums/AIDS/Fatigue/Archive/Help/Q191583.html. Accessed June 24, 2009.
New York City Department of Health and Mental Hygiene. "Health Department study shows doctors are often in the dark about patient's sexual behavior." Press Release www.nyc.gov/html/doh/html/pr2008/pr052-08.shtml. Accessed June 24, 2009.
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