You may be reading this because you or someone you care about learned they have anal cancer. Or maybe you’re curious about your risk of getting anal cancer.
It’s important to get to know the signs of anal cancer. It’s best if we can catch it early, when it may be easier to treat. But at MSK, we have treatment options for anal cancer at every stage.
This guide is a good place to learn about what causes anal cancer and how to prevent anal cancer. You can learn about the signs and symptoms of anal cancer.
This information can help you get ready to talk with your healthcare provider and understand your next steps.
The anus is the opening where stool (poop) leaves the body.
The anus is different from your buttocks (butt), the 2 mounds of fat and muscle you sit on. The anus is at the end of the rectum, a muscle that holds stool until you have a bowel movement. The sphincter muscle keeps the anus closed until you need to poop.
Anal cancer is not the same as rectal cancer. Cancer of the anus, or anal cancer, is rare. Anal cancer is more common among people assigned female at birth than male at birth.
About 9 out of every 10 cases of anal cancer are caused by the human papillomavirus (HPV). This is a common virus that is sexually transmitted. That means you can get HPV when you have sex.
You can learn more about HPV or watch a video about HPV vaccine facts.
It’s important to go to your doctor right away if you notice something is wrong.
You may not have any symptoms of anal cancer. If you do, often the first sign is bleeding from the anus. There are other signs, including itching on or inside your anus.
Anal cancer often is diagnosed after you have symptoms. Talk to your doctor right away if you notice something is wrong.
Radiation therapy and chemotherapy are common treatments for anal cancer. Surgery and immunotherapy are sometimes used to treat anal cancer.
What’s inside your anus? Knowing the anatomy of the anus can help you better understand where anal cancer starts. Anatomy (uh-NA-toh-mee) means the parts of a structure, such as the anus.
The rectum is a holding area for waste (poop) until it leaves your body through your anus.
The rectum and the anus are connected by the anal canal. This tube is about 1.5 to 2 inches (3.8 to 5 cm) long and includes the sphincter muscles.
The anal verge is where the anal canal connects to the outside skin of the anus. The perianal skin is outside and around the anal verge.
The anus is the final part of the digestive process.
After you swallow, food moves to your esophagus (ee-SAH-fuh-gus). This long tube carries food from your mouth to your stomach. There, it starts to digest (break down).
The food next moves to the small intestine. The intestines absorb many nutrients. Anything that’s not absorbed is called waste.
The waste moves to your colon, then the rectum, and is held until it leaves through the anus.
Parts of the anus, rectum, and butt.
Anal cancer often starts in the anus’ tissues or the lining of the anal canal. Anal cancers are grouped by where they start, in the anal canal or the perianal skin.
Most anal cancers start in the squamous (SKWAY-mus) cells in the inner lining of the anal canal. Anal cancer starts when healthy cells change and grow out of control.
These changes often happen because the cells are harmed by an infection with HPV. At first, the changes do not cause any symptoms. Anal cancer can grow slowly over a few years.
A risk factor is anything that raises your chance of getting a disease, such as cancer.
There are some risk factors that you cannot control. These include your age, race, or the genes you were born with.
There are other risk factors that you may be able to change. Research shows that having healthy habits can lower your risk for cancer.
HPV is the most common virus that is sexually transmitted (you can get it when you have sex). Many people have HPV but do not know it. The virus is not active in their body.
HPV infection can lead to some cancers. HPV causes about 9 out of every 10 cases of anal cancer.
Your risk of getting anal cancer from HPV depends on the kind of HPV you have. There are more than 150 kinds of HPV. Some cause warts on the skin, mouth, or genitals, but rarely cancer. HPV 16 is the kind most often linked to anal cancer.
Your chance of getting anal cancer is higher if:
Anal sex does not cause anal cancer, but it can put you at higher risk. Learn more.
Smoking raises your risk for many types of cancer, including anal cancer.
You’re at higher risk for anal cancer if you:
Smoking also can make it harder for your immune system to fight HPV infections.
Learn more about cancer and tobacco use.
If you smoke, it’s never too late to quit or cut back. Learn how MSK’s Tobacco Treatment Program can help.
Your risk may be higher if you:
There are some steps you can take to lower your risk for anal cancer. There also are some risk factors that you cannot control.
Research shows that some healthy habits can lower your risk. Making healthier choices in your everyday life can help.
Our Tobacco Treatment Program has experts who can help you quit smoking. It’s open to people who never had cancer or a disease linked to tobacco. It also welcomes anyone who has cancer, and cancer survivors. Our program offers treatment options to help you quit, such as counseling and medicine.
Anal sex does not cause anal cancer, but it can raise your risk for it.
Anal sex can make it easier to spread HPV, which is the main cause of anal cancer.
Most people get HPV at some point, and your body often clears it on its own.
But sometimes the virus causes cell changes that can lead to cancer. Using condoms and getting the HPV vaccine can help lower your risk.
Regular check-ups are even more important if you have other risk factors, such as HIV.
MSK has experts in anal cancer diagnosis, treatment, and follow-up care.
Anal cancer often does not cause symptoms in the early stages. You may not have any symptoms of anal cancer. If you do, for many people the first sign is bleeding from the anus.
There are other signs to watch for. But they may be caused by other things that are not cancer. Anal fissures and hemorrhoids have similar symptoms to anal cancer but are not cancer. For example, they can cause anal discomfort or bleeding. It’s important to see a healthcare provider for a diagnosis if you have any anal cancer symptoms.
Finding anal cancer at an early stage can make it easier to treat. Read more about how anal cancer is diagnosed.
If you have 1 or more of these symptoms, it does not mean you have anal cancer. Visit your healthcare provider if you notice these possible signs of anal cancer, and they last for 2 weeks:
Early and common signs and symptoms of anal cancer include:
MSK's free, online Patient and Community Education Library has more than 1,200 written and video resources about cancer care. MSK experts explain topics such as treatments, procedures, side effects, screening, and prevention. Our information is in English, Spanish, Russian, Chinese, and other languages.
