Anal Cancer

What is anal cancer?

Anal cancer (also known as carcinoma of the anal canal) develops in your anus’ tissues or the lining of your anal canal. Your anal canal connects your anus (the opening) to your rectum (the lower part of your digestive system). Your anus is where poop leaves your body. Healthcare providers can cure anal cancer if they detect and treat it early on.

Types of anal cancer

There are two types of anal cancer — squamous cell carcinoma and adenocarcinoma. Squamous cell carcinoma is the most common anal cancer type. Squamous cell carcinoma in anal cancer is different from skin cancer that starts in the top layer of your skin.

Is anal cancer common?

No, it’s not. The American Cancer Society estimates more than 9,000 people in the United States will receive an anal cancer diagnosis in 2023. (The ACS estimates include anal cancer, anorectal cancer and anal canal cancer.) In comparison, an estimated 153,000 people will learn they have colon cancer in 2023.

What are the symptoms of anal cancer?

Anal cancer symptoms may feel like common issues like a persistent itch in your anus. Other symptoms may include:

• Rectal bleeding, especially during bowel movements.
• A lump or mass. (An anal cancer lump can appear at your anal opening).
• Pain.
• Seeing a change in your bowel movements, such as frequency or consistency of your stools (poop).
• Leaking stool.
• Feeling like you constantly need to poop (tenesmus).

Many things can cause these symptoms. Having one or more doesn’t mean you have anal cancer. But you should talk to a healthcare provider if you have symptoms like these that get worse or don’t go away within a few days.

It’s normal to feel a little self-conscious, embarrassed or uncomfortable talking to your healthcare provider about some anal cancer symptoms, like having an itchy anus. Lots of things may cause anal cancer, so please know there’s nothing about having anal cancer symptoms that should make you feel ashamed. Your healthcare providers are here to help you with all your health concerns, including anal cancer symptoms.

What causes anal cancer?

The exact cause of anal cancer is unknown. However, there are certain risk factors associated with the disease. For example, most anal cancer cases are linked to certain types of human papilloma virus (HPV). But it’s important to note that the majority of people with HPV don’t get anal cancer.

Risk factors

In addition to HPV, there are other risk factors that could increase your chance of developing anal cancer, including:

• Taking immunosuppressants. These are medications that stop your immune system from damaging healthy cells.
• Having HIV (human immunodeficiency virus). HIV increases your risk of anal cancer because it affects your immune system and because HIV may happen if you have unprotected anal sex.
• Engaging in anal sex as the receiving partner. This is true for both men and people assigned male at birth (AMAB) and women and people assigned female at birth (AFAB). In general, having multiple partners for any type of sex increases your risk for HPV, and therefore your risk of anal cancer.
• Not being vaccinated against HPV. Some forms of HPV are commons anal cancer causes.
• Being age 55 and older. Providers typically detect anal cancer in people in this age group.
• Smoking. People who smoke are more likely to develop cancer of all kinds.
• Having a disease or needing medication that compromises your immune system. For example, people who are organ recipients must take medicine to prevent organ rejection.
• Having an anal fistula (an abnormal opening), which goes from your anus to the skin around your anus.
• Having other cancers, including vulvar, vaginal or cervical cancer.

What are the complications of anal cancer?

Left untreated, anal cancer may spread (metastasize) to nearby tissues. Rarely, it can spread to your lungs or liver.

How is anal cancer diagnosed?

A healthcare provider will ask you about your symptoms, including how long you’ve had them. They’ll ask about your medical history, including conditions that affect your immune system. They may also ask about your sexual activity.

What tests will be done to diagnose this condition?

Your provider will do a digital rectal examination. They’ll do an anal Pap test or biopsy to obtain cells for a medical pathologist to examine under a microscope. (Women and people AFAB may have pelvic examinations.) Your provider will also do endoscopic tests and imaging tests.

Endoscopic tests

Providers do endoscopic tests to look inside your rectum and anus. They do these tests using special instruments that are thin, flexible tubes that have a light, a lens and a video camera. They may take tissue samples (biopsy) for pathologists to examine. Endoscopic tests include:

• Anoscopy, which involves providers using a short lighted tube called an anoscope to look at your anus and lower rectum.
• Flexible sigmoidoscopy to check for tumors and polyps in your rectum and anus.
• Colonoscopy to look at your entire colon for signs of tumors and polyps.

Imaging tests

Imaging tests help providers learn more about tumors, including tumor size and specific location. Imaging tests may include:

• Magnetic resonance imaging (MRI) scan.
• Transrectal ultrasound.
• Computed tomography (CT) scan.
• Positron emission (PET) scan.

Anal cancer staging

Healthcare providers use cancer staging systems to plan treatment and set prognoses, or what you can expect to happen after treatment. They consider factors like tumor size, if there’s cancer in your lymph nodes and whether the tumor has spread or metastasized. There are five stages of anal cancer:

Stage 0

There are abnormal cells in your anus’ mucosa, which is the innermost lining of your anus. The abnormal cells aren’t cancerous but may become cancerous. Stage 0 anal cancer is also called high-grade squamous intraepithelial lesion (HSIL).

Stage I

Cancer cells have formed a tumor that measures 2 centimeters or less, or about the size of a peanut.

Stage II

Stage II anal cancer is divided into two stages:

• Stage IIA means there’s a tumor that’s larger than 2 centimeters but smaller than 5 centimeters.
• Stage IIB means that a tumor is 5 centimeters — about the size of a lime — but hasn’t spread from your anus.

Stage III

Stage III is divided into three stages:

• Stage IIIA, when a tumor is 5 centimeters or smaller and has spread to lymph nodes in your anus or groin.
• Stage IIIB, when anal cancer spreads to nearby organs like your vagina, urethra or bladder.
• Stage IIIC, when there’s cancer in nearby organs and it’s spread to lymph nodes near your anus or groin.

Stage IV

There’s cancer in your lymph nodes that are far away from your anus and in distant organs like your lungs or your liver.

How is anal cancer treated?

Anal cancer treatment depends on the type and cancer stage, but may include:

Radiation therapy

Providers treat anal cancer with external beam radiation therapy (EBRT). Types of EBRT include:

• Intensity-modulated radiation therapy (IMRT), which sends multiple energy beams of different strengths to a tumor.
• Stereotactic body radiation therapy (SBRT), which targets small tumors without damaging nearby healthy tissue.
• Three-dimensional conformal radiation therapy (3D-CRT) that creates a three-dimensional picture of tumors.
• Brachytherapy, which is internal radiation therapy.

Chemotherapy

Healthcare providers often combine chemotherapy and radiation therapy as initial anal cancer treatment. The combined treatments often eliminate anal cancer, so you don’t need surgery.

If you do need surgery, you may have chemotherapy beforehand to shrink the tumor (neoadjuvant chemotherapy) or after surgery to kill any remaining cancer cells (adjuvant chemotherapy).

Surgery

Laparoscopic abdominoperineal resection is a minimally invasive surgery used to treat anal cancer that comes back (recurs) or didn’t respond to radiation therapy and/or chemotherapy. It involves removing your anus, rectum and colon.

If you have this surgery, your surgeon will also do a permanent colostomy so you can eliminate poop into a bag or pouch attached to your body.

Immunotherapy

If you have late-stage anal cancer, your provider may recommend immunotherapy to help you manage your symptoms. Immunotherapy helps your body fight cancer.

What are treatment side effects?

Most cancer treatments may cause side effects. For example, chemotherapy and radiation therapy side effects may include skin irritation, pain in your anal area, fatigue, chemotherapy brain fog, nausea and vomiting.

What are treatment complications?

Healthcare providers may treat anal cancer with surgery. Surgery complications may include:

• A reaction to anesthesia.
• Excessive bleeding.
• Infection.

Can anal cancer be prevented?

There’s no guaranteed way to prevent anal cancer, but you can reduce the chance of developing it by taking the following steps:

• Don’t smoke. If you do smoke, find ways to help yourself quit. Your healthcare provider can also help you.
• Practice safe sex. Make sure you use condoms if you engage in anal sex.
• Get the human papilloma virus (HPV) vaccine if you’re eligible for it. This vaccine not only prevents anal cancer, but also cancers of the mouth and throat, cervical cancer and penile cancer.

What are anal cancer survival rates?

Anal cancer survival rates are estimates of the percentage of people with the condition who were alive five years after diagnosis. Rates vary depending on whether a provider diagnoses and treats the condition before it spreads. Overall, 70% of people with anal cancer were alive five years after diagnosis, according to the National Cancer Institute (U.S.). Survival rates by cancer location include:

It’s important to remember that survival rates are based on the experiences of large groups of people who may have different health issues. What’s true for them may not be true for you. If you have questions, ask your provider to explain what you can expect.

When should I see my healthcare provider?

If you’re receiving treatment for anal cancer, you should follow the appointment schedule your healthcare provider set up and contact them as directed. For instance, your healthcare provider might tell you to call if you have pain or a fever.

Sometimes anal cancer treatment involves surgery to remove parts of your digestive system and to provide you with a permanent colostomy so your poop can leave your body. Living with a permanent colostomy can be challenging, but you won’t be alone. Your healthcare team will help you as you get used to managing how you poop and living a full and normal life after anal cancer surgery.

What questions should I ask my healthcare provider?

If you have anal cancer, you may want to ask your provider the following questions:

• What type of anal cancer do I have?
• What’s my cancer stage?
• What are my treatment options?
• If I need surgery, what kind of surgery do you recommend?

What’s the difference between anal cancer and anal dysplasia?

The difference is anal dysplasia isn’t cancer, but it may pave the way for anal cancer. In anal dysplasia, cells in your anus become abnormal. Over time, these abnormal cells could start multiplying, creating cancerous tumors.

How is anal cancer different from rectal cancer and colon cancer?

Your anus, rectum and colon are all parts of your digestive system. But the cells that make up each parts’ tissue are very different, which means healthcare providers treat these cancers in different ways.

A note from Cleveland Clinic

Anal cancer is cancer in your anus — the part of your body that you wipe after you poop. The most common symptoms are bleeding from your anus or anal itching — things you may hesitate to discuss with a healthcare provider. But anal cancer is most easily treated when providers detect and treat it early, before it spreads. If you notice symptoms like an anal itch that won’t go away, talk to a provider. They’re ready to help.