Anal cancer is found in or on the anus. The anus is part of the gastrointestinal tract and is the opening at the end of the large intestine, below the rectum, where bowel movements leave the body. The anus is made up of different types of cells, and each type can become cancerous. Therefore, there are several different types of anal cancer:

• Squamous cell carcinoma is the most common type of anal cancer. This cancer begins in the outer lining of the anal canal.
  
  
• Cloacogenic carcinoma accounts for about one-quarter of all anal cancers. This cancer arises between the outer part of the anus and the lower part of the rectum. Cloacogenic cell cancer likely starts from similar cells as squamous cell cancer and is treated similarly.
  
  
• Adenocarcinoma arises from the glands that make mucous, located under the anal lining.
  
  
• Basal cell carcinoma is a type of skin cancer that can appear in the perianal (around the anus) skin.
  
  
• Melanoma begins in cells in the skin or anal lining that darken the skin.

A tumor of the anus can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other areas of the body). There are also growths that can occur in or around the anus, such as polyps or warts. While these growths are not cancerous, some may become cancerous over time.

Statistics

In 2009, an estimated 5,290 adults (2,100 men and 3,190 women) in the United States will be diagnosed with anal cancer. It is estimated that 710 deaths (260 men and 450 women) from this disease will occur this year.

The overall five-year relative survival rate (percentage of people who survive at least five years after the cancer is detected, excluding those who die from other diseases) of people with anal cancer is 66%. The five-year survival rate of people with cancer that has not spread is 80%. The five-year relative survival rate for tumors that have spread to the area around the anus and those that have spread to more distant body parts is 61% and 29%, respectively. The five-year relative survival rate may be lower for people who have human immunodeficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS).

Cancer survival statistics should be interpreted with caution. These estimates are based on data from thousands of cases of this type of cancer in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with anal cancer. Because the survival statistics are measured in five-year intervals, they may not represent advances made in the treatment or diagnosis of this cancer.

Statistics adapted from the American Cancer Society's publication, Cancer Facts & Figures 2009, and the National Cancer Institute Surveillance Epidemiology and End Results (SEER) database. 

Find out more about basic cancer terms used in this section.

A risk factor is anything that increases a person’s chance of developing cancer. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor may help you make more informed lifestyle and health-care choices.

The following factors may raise a person’s risk of developing anal cancer:

Human papillomavirus (HPV) infection. HPV causes bumps on the skin around the anus commonly called venereal warts. There are different types or strains of HPV, and some strains are more strongly associated with anal cancer than others. HPV is most often spread through sexual contact, particularly anal intercourse. People with many sex partners have an increased risk of contracting HPV.

Age. Most cases of anal cancer are diagnosed in people between 50 and 80.

Frequent anal irritation. Frequent anal redness, swelling, and soreness may increase the risk of developing anal cancer.

Anal fistula. An anal fistula is an abnormal tunnel between the anal canal and the outer skin of the anus that often drains pus or liquid, which can soil or stain clothing. An anal fistula may irritate the outer tissues or cause discomfort. An anal fistula may increase the risk of developing anal cancer.

Cigarette smoking. Cigarettes can cause harm throughout the body, because chemicals from cigarettes can enter the bloodstream and affect nearly every organ and tissue in the body. Smokers are about eight times more likely to develop anal cancer than nonsmokers.

Lowered immunity. People with diseases or conditions affecting the immune system, such as HIV or organ transplantation, and people who take immunosuppressive drugs that make the immune system less able to fight disease, are more likely to develop anal cancer.

Even though some people who have no risk factors develop anal cancer, there are ways to prevent or reduce your risk of developing anal cancer.

• Avoid anal sexual intercourse, which carries an increased risk of HPV and HIV infection.
  
  
• Limit the number of sex partners, because having many partners increases the risk of HPV and HIV infection.
  
  
• Use a condom. However, even though condoms can protect against HIV, they cannot fully protect against HPV.
  
  
• Stop smoking.

Anal cancer screening

Anal cytology is a test being developed that doctors can use for people who have a high risk of contracting a sexually transmitted disease (STD) such as HPV and HIV. The test is similar to a Pap test, which looks for cervical cancer, except this test looks for anal cancer. The doctor can swab the anal lining and look at the cells on the swab under a microscope to find early cellular changes that might lead to cancer or may diagnose cancer from this swab. Some doctors are advocating the routine use of this test for men who have HIV and who have sex with men and for other people who are at high risk for developing anal cancer.

People with anal cancer may experience the following symptoms. Sometimes, people with anal cancer do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not cancer. If you are concerned about a symptom on this list, please talk with your doctor.

• Bleeding from the anal area
  
  
• Pain or pressure in the anal area
  
  
• Itching or discharge from the anus
  
  
• A lump or swelling near the anus
  
  
• A change in bowel habits or change in the diameter of the stool

Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

In addition to a physical examination, the following tests may be used to diagnose anal cancer:

Digital rectal examination (DRE). During this test, the doctor inserts a gloved finger into the anus to feel for lumps or abnormalities. General cancer guidelines suggest men have a DRE annually after the age of 50 and women have one during routine pelvic examinations. If you are at higher risk for developing anal cancer, your doctor may perform a DRE more often.

Anoscopy. If the doctor feels a suspicious area during a DRE, an anoscope (a thin, lighted, flexible tube) may be inserted into the anus to see the abnormality. Similarly, a proctoscope can be used to view the rectum (a procedure called a proctoscopy).

Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). The type of biopsy performed will depend on the location of the cancer. For instance, an excisional biopsy can remove the entire lump if it is small and does not extend into other tissues. Lymph nodes may also be examined in a biopsy.

Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs. In an anal ultrasound, an ultrasound wand is inserted into the anus to obtain the pictures.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images.

X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help determine if the cancer has spread to the lungs.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.

Staging is a way of describing a cancer, such as where it is located, if or where it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the cancer’s stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis (chance of recovery). There are different stage descriptions for different types of cancers.

One tool that doctors use to describe the stage is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself, the lymph nodes around the tumor, and if the tumor has spread to other parts of the body. The results are combined to determine the stage of cancer for each person. There are five stages: stage 0 (zero) and stages I through IV (one through four). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.

TNM is an abbreviation for tumor (T), node (N), and metastasis (M). Doctors look at these three factors to determine the stage of cancer:

• How large is the primary tumor and where is it located? (Tumor, T)
  
  
• Has the tumor spread to the lymph nodes? (Node, N)
  
  
• Has the cancer metastasized (spread) to other parts of the body? (Metastasis, M)

Tumor. Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below:

TX: The primary tumor cannot be evaluated.

T0: There is no tumor.

Tis: Refers to carcinoma in situ (which is very early cancer that has not spread.)

T1: The tumor is no larger than 2 centimeters (cm).

T2: The tumor is larger than 2 cm, but not larger than 5 cm.

T3: The tumor is larger than 5 cm.

T4: The tumor has invaded other organs, such as the vagina, urethra, or bladder.

Node. The “N” in the TNM staging system stands for lymph nodes, the tiny, bean-shaped organs that help fight infection. Lymph nodes near the anus are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes.

NX: Regional lymph nodes cannot be evaluated.

N0 (N plus zero): There is no regional lymph node metastasis.

N1: Cancer had spread to the perirectal (around the rectum) lymph nodes.

N2: Cancer has spread to the internal iliac (pelvic) and/or the inguinal lymph nodes (lymph nodes in the groin just under the skin surface) on the same side of the body.

N3: Cancer had spread to the perirectal and inguinal lymph nodes and/or the internal iliac and/or inguinal lymph nodes on both sides of the body.

Distant metastasis. The “M” in the TNM system indicates whether the cancer has spread to other parts of the body.

MX: Distant metastasis cannot be evaluated.

M0 (M plus zero): There is no distant metastasis.

M1: There is metastasis to other parts of the body.

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications.

Stage 0: Abnormal cells are in the first layer of the lining of the anus only. The abnormal cells may become cancer. This stage is also called carcinoma in situ (Tis, N0, M0).

Stage I: The tumor is no larger than 2 cm with no spread to lymph nodes or other parts of the body (T1, N0, M0).

Stage II: The tumor is larger than 2 cm with no spread to lymph nodes or other parts of the body (T2 or T3, N0, M0).

Stage IIIA: The tumor may be any size and has spread to either nearby lymph nodes or to organs, such as the vagina, urethra, and bladder (T1, T2, T3; N1, M0; or T4, N0, M0).

Stage IIIB: The tumor may be any size and has spread to nearby lymph nodes or organs; lymph nodes in the pelvis and/or groin; or to lymph nodes near the rectum, in the groin and/or on both sides of the pelvis or groin (T4, N1, M0; or Any T, N2 or N3, M0).

Stage IV: The tumor may be any size and has spread to lymph nodes and to distant parts of the body (Any T, Any N, M1).

Recurrent: Recurrent cancer is cancer that comes back after treatment.

Grading

Histologic grade (G). In addition to the TNM system, doctors may also assign a histologic grade to the cancer. Histologic grade indicates how closely the cancer cells resemble normal tissue under a microscope. A tumor's grade is described using the letter “G” and a number.

GX: The tumor grade cannot be identified.

G1: Describes cells that look more like normal tissue cells (well differentiated).

G2: The cells are somewhat different from normal cells (moderately differentiated).

G3: The cells do not look like normal cells (poorly differentiated).

G4: Describes tumor cells that barely resemble normal cells (undifferentiated).

Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, Sixth Edition (2002) published by Springer-Verlag New York, www.springer-ny.com.

The treatment of anal cancer depends on the size and location of the tumor, whether the cancer has spread, and the patient’s overall health, including whether the patient has HIV. In many cases, a team of doctors will work with the patient to determine the best treatment plan.

This section outlines treatments that are the standard of care (the best treatments available) for this specific type of cancer. Patients are also encouraged to consider clinical trials when making treatment plan decisions. A clinical trial is a research study to test a new treatment to prove it is safe, effective, and possibly better than standard treatment. Your doctor can help you review all treatment options. For more information, visit the Clinical Trials section.

For anal cancer, there are three main types of treatment: surgery, radiation therapy, and chemotherapy. Each treatment is described below.

Surgery

The type of surgery for anal cancer depends on the stage of the cancer. Anal carcinoma in situ or early-stage cancer can often be treated by removing the abnormal cells and a small area of the surrounding normal tissue (called a margin). Afterward, patients should receive regular follow-up screening to identify and remove any new abnormal cells.

Most patients with later stages of anal cancer were treated surgically before effective chemotherapy and radiation therapy were developed for anal cancer. However, studies have shown similar cure rates between surgical treatment and the combination of radiation therapy and chemotherapy. Now, most patients will have a biopsy (which may require some level of surgery; see Diagnosis) followed by chemotherapy and radiation therapy without further surgery. Many patients can avoid major surgery with this type of combined treatment.

In cases where a patient cannot have chemotherapy or radiation therapy, surgery may be recommended. Surgery may also be recommended if the cancer remains after initial treatment or returns after treatment has been completed. A persistent or recurring tumor may be treated with an abdominoperineal resection, which is the surgical removal of the anus, rectum, and part of the colon. This procedure results in a colostomy (an opening on the abdominal wall to allow feces to be collected in a bag). Lymph nodes may also be removed during this procedure.

Radiation therapy

Radiation therapy is the use of high-energy x-rays or other particles to kill cancer cells. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. When radiation treatment is given using implants, it is called internal radiation therapy or brachytherapy.

Side effects of radiation therapy may include fatigue, mild skin reactions, upset stomach, temporary anal irritation, loose bowel movements, and discomfort when having a bowel movement. Scar tissue may form from damage to anal tissue, which may interfere with bowel function. Most side effects go away soon after treatment is finished.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. Systemic chemotherapy is delivered through the bloodstream, targeting cancer cells throughout the body. It is particularly valuable for treating anal cancer when given in combination with radiation therapy. The combined treatment allows the use of lower radiation doses and improves the likelihood of completely destroying the tumor. Chemotherapy for anal cancer usually consists of a combination of drugs. The main chemotherapy drugs given for anal cancer are fluorouracil (5-FU, Adrucil) and mitomycin C (Mutamycin), or fluorouracil and cisplatin (Platinol). The side effects of chemotherapy depend on the individual and the dose used, but can include fatigue, risk of infection, nausea and vomiting, loss of appetite, and diarrhea. These side effects usually go away once treatment is finished.

Patients with anal cancer and HIV may be treated with lower doses of chemotherapy and radiation therapy, depending on the degree the patient’s immune system is compromised by the HIV.

The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications prescribed for you, their purpose, and their potential side effects or interactions with other medications. Learn more about your prescriptions through Cancer.Net's Drug Information Resources, which provides links to searchable drug databases.

Recurrent anal cancer

The treatment of recurrent anal cancer depends on the original treatment. For example, a patient who initially had chemotherapy and radiation therapy may be treated with surgery if the cancer recurs.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: During Treatment.

Doctors and scientists are always looking for better ways to treat patients with anal cancer. A clinical trial is a way to test a new treatment to prove that it is safe, effective, and possibly better than a standard treatment. Patients who participate in clinical trials are among the first to receive new treatments before they are widely available. However, there is no guarantee that the new treatment will be safe, effective, or better than a standard treatment.

Patients decide to participate in clinical trials for many reasons. For some patients, a clinical trial is the best treatment option available. Because standard treatments are not perfect, patients are often willing to face the added uncertainty of a clinical trial in the hope of a better result. Other patients volunteer for clinical trials because they know that finding new drugs and other therapies is the only way to make progress in treating anal cancer. Even if they do not benefit directly from the clinical trial, their participation may benefit future patients with anal cancer.

To join a clinical trial, patients must complete a learning process known as informed consent. During informed consent, the doctor should list all of the patient’s options, so the person understands how the new treatment differs from the standard treatment. The doctor must also list all of the risks of the new treatment, which may or may not be different from the risks of standard treatment. Finally, the doctor must explain what will be required of each patient in order to participate in the clinical trial, including the number of doctor visits, tests, and the schedule of treatment. Learn more about Clinical Trials, including patient safety, phases of a clinical trial, deciding to participate in a clinical trial, questions to ask the research team, and links to find cancer clinical trials.

Cancer and its treatment can cause a variety of side effects. However, doctors have made major strides in recent years in reducing pain, nausea and vomiting, and other physical side effects of cancer treatments. Many treatments used today are less intensive but as effective as treatments used in the past. Doctors also have many ways to provide relief to patients when such side effects do occur.

Fear of treatment side effects is common after a diagnosis of cancer, but it may be helpful to know that preventing and controlling side effects is a major focus of your health-care team. Before treatment begins, talk with your doctor about possible side effects of the specific treatments you will be receiving. The specific side effects that can occur depend on a variety of factors, including the type of cancer, its location, the individual treatment plan (including the length and dosage of treatment), and the person’s overall health.

Ask your doctor which side effects are most likely to happen (and which are not), when side effects are likely to occur, and how they will be addressed by the health-care team if they do happen. Also, be sure to communicate with the doctor about side effects you experience during and after treatment. For more information on the most common side effects of cancer and different treatments, along with ways to prevent or control them, visit, Cancer.Net’s section on Managing Side Effects, based on ASCO’s curriculum.

In addition to physical side effects, there may be psychosocial (emotional and social) effects are well. Learn more about the importance of addressing these needs in Cancer.Net’s section on Caring for the Whole Patient.

For more information on late effects or long-term side effects, please read the After Treatment section or talk with your doctor.

After treatment for anal cancer ends, talk with your doctor about developing a follow-up care plan. This plan may include regular physical examinations and/or medical tests to monitor your recovery for the coming months and years.

Regular examinations are important following treatment of anal cancer to detect any local recurrence of the cancer or spread to other parts of the body. The examinations usually are scheduled for every few months for the first two or three years following treatment, and then at less frequent intervals. In addition to physical examination, other procedures (such as proctoscopy), imaging studies (such as CT scanning), and blood tests may be done depending on the treatment given.

Damage to the anus, bowel, or bladder can occur from the use of radiation therapy, resulting in diarrhea, problems with urination, or problems having bowel movements. Surgery or combined use of radiation therapy and chemotherapy can result in impotence in men (the inability to get or maintain an erection). Talk with your doctor about ways to prevent or manage side effects from treatment.

People recovering from anal cancer are encouraged to follow established guidelines for good health, such as maintaining a healthy weight, not smoking, eating a balanced diet, and having recommended cancer screening tests. For anal cancer survivors who smoke, quitting smoking is strongly encouraged. Talk with your doctor to develop a plan that is best for your needs. Moderate physical activity can help rebuild your strength and energy level. Your doctor can help you create an appropriate exercise plan based upon your needs, physical abilities, and fitness level. Learn more about Healthy Living After Cancer.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: After Treatment.

Research for anal cancer is ongoing. The following advances may still be under investigation in clinical trials and may not be approved or available at this time. Always discuss all diagnostic and treatment options with your doctor.

Radiosensitizers. Drugs that make tumor cells more susceptible to radiation therapy are being explored as a way to enhance the effectiveness of radiation therapy.

HPV vaccines. Because most cases of anal cancer are likely caused by HPV, an HPV vaccine could potentially prevent many cases of anal cancer from occurring. Currently, an HPV vaccine has been approved by the U.S. Food and Drug Administration to prevent infection by the most common HPV strains that cause cervical cancer in girls and women between ages 9 and 26.

Anal cytology. Like a Pap test, anal cytology looks for abnormal cells in the anal lining. This test may help find anal cancer at the earliest, most treatable stages.

Regular communication with your doctor is important in making informed decisions about your health care. Consider asking the following questions of your doctor:

• What type of anal cancer do I have?
  
  
• What is the stage of my cancer? What does this mean?
  
  
• Can you explain my pathology report (laboratory test results) to me?
  
  
• What are my treatment options?
  
  
• What clinical trials are open to me?
  
  
• What treatment do you recommend? Why?
  
  
• What are the possible side effects of treatment, both in the short term and the long term?
  
  
• How will this treatment affect my daily life? Will I be able to work, exercise, and perform my usual activities?
  
  
• Will I need a colostomy bag?
  
  
• Will there be permanent issues relating to bowel function?
  
  
• Will there be permanent issues relating to sexual function?
  
  
• What are the chances that the cancer will recur?
  
  
• What follow-up tests will I need, and how often will I need them?
  
  
• How can I keep myself as healthy as possible during treatment?
  
  
• What support services are available to me? To my family?

Rare Cancer Alliance
1649 N. Pacana Way
Green Valley, AZ 85614
www.rare-cancer.org

United Ostomy Associations of America (UOAA)
P.O. Box 66
Fairview, TN 37062-0066
Toll Free: 800-826-0826
www.uoaa.org

Colon Cancer Alliance
1200 G Street, NW; Ste. 800
Washington, DC 20005
Phone: 202-434-8980
www.ccalliance.org

View all of Cancer.Net's Patient Information Resources.