Anal Cancer

What is anal cancer?

Anal cancer starts in the anus, the last part of the digestive or gastrointestinal tract. The anus is at the end of the rectum and is responsible for passing stool from the body. The anus is made up of the sphincter and flat cells that form the lining of the inside of the anus. Most anal cancers start in these flat lining cells, which are also called squamous cells. The lower part of the anus, where it meets the skin, is called the anal margin.

Cancer of the anus starts in the cells of the anus. Different types of tumors can form in the anus. Some of these tumors are not cancer.

How common is anal cancer?

  • An estimated 9,760 people will develop anal cancer in the United States this year
  • Anal cancer is most commonly found in people age 35 and older
  • The average age to receive a diagnosis is 60
  • Women are more likely to develop anal cancer


Types of anal cancer tumors include:

  • Benign or noncancerous anal tumors. Polyps are small growths that may be flat or bumpy. Or they may look like mushrooms. They are not cancer. There are different types of polyps depending on their location and their cause. Inflammatory polyps, lymphoid polyps, and skin tags (fibroepithelial polyps) are examples of noncancerous (benign) polyps. Other types of benign tumors include adnexal tumors, leiomyomas, and granular cell tumors. They also include hemangiomas, lipomas, and schwannomas. These are all rare.
  • Anal warts (condylomas). These are noncancerous growths that may occur just outside the anus and in the lower anal canal. They are caused by infection with a human papilloma virus (HPV). People who have had anal warts are more likely to get anal cancer.
  • Precancerous lesions. Many people who get the most common type of anal cancer (squamous cell carcinoma) first had some patches of irregular cells. Your healthcare provider may call these lesions anal intraepithelial neoplasia (AIN). Each year, a small percentage of people with AIN get invasive cancer.
  • Malignant anal tumors. These are cancerous tumors. The most common type is squamous cell carcinoma. This type of anal cancer starts in the skin cells around the anus (called the perianal skin) and most of the anal canal. Adenocarcinomas are another type of anal tumor. They account for a small number of cases of anal cancer. Other types of malignant anal tumors are very rare.


What are the symptoms of anal cancer?

Bleeding from the rectum is the most common symptom of anal cancer. But sometimes anal cancer does not cause any symptoms at all.

Other anal cancer symptoms include:

  • Pain or pressure around your anus
  • Itching around your anus
  • Discharge from your anus
  • Bleeding from your anus
  • Swollen lymph nodes in your anal or groin area
  • A lump or swelling near your anus
  • Narrower stools
  • An increase or decrease in bowel movements
  • Loss of control of bowel movements (incontinence)

Anal cancer vs. hemorrhoids

Anal cancer and hemorrhoids share many of the same symptoms, particularly bleeding from the anus.

Having anal cancer means there is one or more tumors growing that started in the anus. Hemorrhoids are swollen veins in the anus and rectum.

It’s likely hemorrhoids if these pertain to you:

  • A swollen vein or lump is felt or visible with a mirror
  • Currently pregnant
  • Constipation
  • History of hemorrhoids
  • Often strain to have a bowel movement
  • Symptoms get better with home treatment
  • Symptoms don’t get worse

If you have symptoms of hemorrhoids or anal cancer, it’s best to talk with your health care provider just to be sure. Hemorrhoids can be easily treated.

Risk Factors

What causes anal cancer?

The causes of anal cancer can depend on the individual and their risk factors.

People who are most at risk for developing anal cancer include:

  • Anyone who has a weakened immune system, such as people who are on immunosuppression medicines after organ transplant or those who are on steroids for a long time
  • Anyone who is HIV-positive
  • Anyone with a history of anal warts
  • Having many sexual partners
  • Men who have sex with men
  • Smoking
  • Women with a history of cervical, vaginal or vulvar cancer
  • Women older than age 45 who are HPV 16 positive
  • Anyone who hasn’t been vaccinated against HPV


The best way to prevent anal cancer is early detection. If you’re at high risk, it’s important to watch for the early signs of anal cancer and get tested. Other ways you can help prevent anal cancer include:

  • Getting vaccinated against HPV
  • Quitting smoking
  • Taking all medicines if infected with HIV
  • Taking care to practice safe sex


How is anal cancer diagnosed?

If your health care provider thinks you might have anal cancer, certain exams and tests will be needed to be sure. Diagnosing anal cancer starts with your health care provider asking you questions. You'll be asked about your health history, your symptoms, risk factors and family history of disease.

Your provider will complete a physical exam and a digital rectal exam (DRE). They will check the inside of your anus and the lower part of the rectum. A trained health care provider can feel tissue changes such as hard or lumpy areas.

What tests might I need?

If your health care provider feels anything abnormal during a DRE, or if you have symptoms that could be caused by anal cancer, tests will be done to learn more. One or more of these tests might be used:

  • Anoscopy. For this test, your provider puts a short, lighted tube into your anus to look at it and the lining of your lower rectum. The tube is lubricated before it's put in. You're awake for this, and it usually doesn't hurt.
  • Proctoscopy. This test is done using a longer lighted tool to look at the inside of your anus and rectum. The lower part of your large intestine can also be seen. The proctoscope is about 10 inches long. The tube is lubricated before it's put in. You may need to use laxatives to empty your bowels before this test. Medicines might be used to make you sleepy during a proctoscopy. Sometimes tiny pieces of suspect tissue can be taken out with tools inside the proctoscope. This is called a biopsy.
  • Colonoscopy. This test uses a longer flexible tube that can see the anus, rectum and entire colon. You will need to take laxatives before this test to clean out the colon. And you will typically be given medicine to make you sleepy so you will not feel anything. Biopsies can be taken through the endoscope if anything suspicious is seen.
  • Biopsy. If your provider sees any tissue changes that could be cancer, a biopsy may be needed. During a biopsy, your provider takes a small piece of tissue from your anus. The tissue is sent to a lab. It’s checked under a microscope and tests are done by a pathologist. A biopsy is the only way to know for sure if a change seen in the anus is cancer or not.

Anal cancer is defined in stages depending on how far along it has progressed or how much it has spread. When diagnosed with anal cancer, you'll be diagnosed as stage 0, 1, 2, 3 or 4. Stages 0, 1 and 2 mean the cancer is localized – it’s only found in the anus. Stages 3 and 4 mean the cancer has spread to other parts of the body. If the cancer has spread to other areas in the anal region, such as the vagina, prostate or bladder, this is considered regional.


How is anal cancer treated?

The type of treatment that's best for you depends on a number of factors. These include the type of tumor, its size, where it is and whether it has spread beyond your anus. Factors also include your age, overall health and what side effects you find acceptable.

Different types of treatment work in different ways. Here is a list of common anal cancer treatments and how they work. You may have more than one of these treatments:

  • Radiation therapy. External radiation therapy is the most common radiation treatment for anal cancer. The beams of radiation are aimed from different angles directly at the tumor.
  • Chemotherapy. Chemo is the use of strong medicines that kill cancer cells. For the treatment of anal cancer, it’s often given as intravenously for four or five days in a row. The aim of the medicine is to shrink the tumor. Chemo combined with radiation therapy is used to treat, and even cure, most anal cancers without surgery.
  • Surgery. Surgery is done to remove the tumor, while leaving as much of the anus as possible intact. In most cases, surgery for anal cancer isn't needed. If surgery is an option for you, know exactly what will be done and how stool will come out of your body after surgery.

Clinical trials

Research is ongoing in the field of anal cancer. New medicines and treatments are tested in clinical trials. Before starting treatment, ask your health care provider if there are any clinical trials you should look into.

Can anal cancer be cured?

When caught early, anal cancer can be cured with treatment. According to the American Cancer Society, the five-year anal cancer survival rate is about 83% when it hasn’t spread and 67% when it has spread to other areas in the same region as the anus.


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