The anus is the opening at the lower end of the large intestine, below the rectum. The anus is formed partly from outer skin layers of the body and partly from intestinal tissues. Two ring-like muscles, called sphincter muscles, control the passage of stool from the body. The anal canal, the part of the anus between the rectum and the anal opening, is about 1 ½ to 2 inches long.
HPV and Anal Cancer
Human papillomavirus (HPV) is a very common virus that men and women can get from sex. More than half of people who are sexually active get HPV at some time in their lives. They often don’t know it because they don’t have symptoms or other health problems. Our immune system can often clear the virus, but certain types of HPV are hard to fight. There are more than 100 types of HPV. Some types of HPV cause common warts of the hands or feet, but these are not usually spread by sex. Other types of HPV may cause warts or changes in the cells of the skin, mouth, or genitals (penis, vagina, or anus). Still other types of HPV can lead to anal cancer or cancer of the cervix in women if not caught early. The types of HPV that cause genital warts are not the same as the types of HPV that cause cancer.
HPV is the main cause of anal cancer. Risk factors for anal cancer include HIV, having anal sex or multiple sex partners, and smoking. People who have weak immune systems, such as those who have had organ transplants or take drugs to suppress their immune systems, also have a higher risk of anal cancer.
More and more people are being diagnosed with anal cancer. People with HIV often have a harder time fighting HPV. Men, as well as women with HIV, should get tested for HPV infection. An anal pap test may help us find changes in cells so that we can prevent or catch anal cancer early.
What is an anal pap test?
An anal pap test is a screening test for both men and women. It looks for changes in the cells of the anus that could lead to anal cancer (very much like pap smears of the cervix in women). The anal pap test does not test for colon or rectal cancer.
How is the anal pap test done?
The anal pap test will take less than 5 minutes. In most cases, it will cause little or no pain.
During this test, we may ask you to lie on your side on an exam table. We may also ask you to bend forward over an exam table. We will insert a swab, which looks like a long, thin Q-tip, about 1 ½ - 2 inches into your anus. We will collect a sample of cells using this swab. We will then send the sample to the lab to look at the cells under a microscope to see if there are any changes. You will receive the results of the test in 1-2 weeks.
What do the results mean?
Negative. The cells are normal. We will repeat the anal pap in one year.
Unsatisfactory. We couldn’t get a complete sample of your cells to get accurate results. We will repeat the anal pap in 3-6 months.
ASCUS (atypical squamous cells of undetermined significance). These cells are not normal, but it is unclear what this means. This is mild and does not mean you have cancer.
LSIL (low grade anal squamous intraepithelial lesion). These cells are not normal. This is mild and does not mean you have cancer.
HSIL (high grade anal squamous intraepithelial lesion). These cells are not normal. This is more sever but does not mean you have cancer.
Squamous carcinoma. This is a rare result. This means the cells show major changes that might be cancer. In this case, we will do a biopsy (take tiny samples of tissue). We will send these samples to a lab to look for cancer under a microscope.
What happens after I receive my results?
If your most recent pap is negative, you still will need to have annual anal pap screenings if you have HIV.
For all other results you will likely be referred to another provider for more testing. Often, this testing includes an office-based procedure known as a high resolution anoscopy (HRA). The HRA involves an exam of the cells within your anal canal and perhaps biopsies.
For HRA, we will ask you to lay on your side for 10-15 minutes while we inspect your anal canal through a small rigid hollow tube called an anoscope. Most patients will not need to be put to sleep for the HRA. This should not be painful. You do not need to do anything to prepare for the HRA and you can resume your normal duties when it is done. We will call you in 1-2 weeks with any results from the HRA and talk about any needed follow-up visits.