Anal cancer is relatively rare. About 8,348 people in the United States are diagnosed with it each year, making it far less common than colorectal, breast, or lung cancers. For the general population, lifetime risk is low. But certain groups face significantly higher rates, and understanding who is most at risk matters for early detection.
Annual Cases and Overall Trends
Based on data from 2018 to 2022, roughly 8,300 new anal cancer cases are diagnosed in the U.S. annually. That number has held relatively steady in recent years. According to the National Cancer Institute, age-adjusted rates for new cases have not changed significantly over the 2014 to 2023 period. For context, colorectal cancer affects more than 150,000 Americans per year, so anal cancer accounts for a small fraction of gastrointestinal cancers overall.
The vast majority of these cancers are squamous cell carcinomas, which develop in the thin, flat cells lining the anal canal. Adenocarcinoma of the anus, by contrast, makes up less than 1% of all anal cancer cases.
The HPV Connection
Human papillomavirus (HPV) drives the overwhelming majority of anal cancers. The CDC estimates that about 91% of anal cancers, roughly 7,600 cases per year, are caused by HPV. Most of these involve high-risk HPV strains, particularly the types targeted by the HPV vaccine. This makes anal cancer one of the most HPV-attributable cancers, even more so than cervical cancer in percentage terms.
HPV vaccination before exposure to the virus is the single most effective way to reduce anal cancer risk. The vaccine covers the high-risk strains responsible for the vast majority of HPV-related anal cancers.
Who Is Most at Risk
While anal cancer can affect anyone, certain populations have a meaningfully higher risk. People living with HIV face elevated rates compared to the general population, and the risk increases over time. A study published in the Journal of the National Cancer Institute tracked cumulative incidence among people diagnosed with HIV. Among men who have sex with men (MSM) diagnosed with HIV before age 30, the chance of developing anal cancer within the first 10 years was 0.17%, compared to 0.04% in other men with HIV and 0.03% in women with HIV.
Those numbers climb substantially over longer time horizons. For the same group of MSM with HIV, the cumulative incidence from 10 to 20 years after HIV diagnosis jumped to 0.88%, roughly a fivefold increase compared to the first decade. Among MSM who had progressed to AIDS, the 10- to 20-year cumulative incidence reached 1.23%. These numbers are small in absolute terms but represent a dramatically higher risk than the general population faces.
Other factors that raise risk include a weakened immune system from any cause (such as organ transplant medications), a history of other HPV-related cancers or precancerous conditions, chronic anal inflammation, and smoking.
Survival Rates by Stage
Anal cancer has a relatively good prognosis when caught early. Five-year relative survival rates based on patients diagnosed between 2015 and 2018 break down as follows:
- Localized (cancer confined to the anus): 85%
- Regional (spread to nearby lymph nodes): 70%
- Distant (spread to other parts of the body): 36%
These numbers reinforce why early detection matters so much. Most anal cancers are treated with a combination of radiation and chemotherapy rather than surgery, and localized disease responds well to this approach. The gap between localized and distant survival is significant, making awareness of symptoms like bleeding, pain, or a lump near the anus worth paying attention to, even though most of these symptoms turn out to be something benign like hemorrhoids.
Screening for High-Risk Groups
There is no routine screening recommendation for the general population because the cancer is uncommon enough that broad screening would not be cost-effective. For people living with HIV, however, clinical guidelines are more specific. The NIH recommends that all adults with HIV be assessed at least once a year for anal abnormalities, including pain, burning, or masses, along with a digital anorectal exam.
For people under 35 with HIV, further testing with standard anoscopy is recommended only if symptoms or visible abnormalities are present. For MSM and transgender women aged 35 and older, and all other people with HIV aged 45 and older, guidelines recommend lab-based screening of anorectal specimens. If those specimens show abnormalities, a referral for high-resolution anoscopy (a magnified visual exam of the anal canal) follows. Where high-resolution anoscopy is not available, ongoing symptom assessment and digital exams remain the recommended approach.
For people not living with HIV who have other risk factors, screening practices vary. Talking with a healthcare provider about personal risk factors, particularly HPV history and immune status, can help determine whether any form of regular monitoring makes sense.