Anal Cancer: Signs, Symptoms, Causes & Treatment

Cancer that develops in the cells and tissue of the skin lining on either the inside or outside of the anus is called anal cancer.

The anus is an opening to the outside of the body from which stool exits the body. It is below the rectum and is the last part of the gastrointestinal tract.

Some confuse anal cancer with rectal cancer due to the proximity, but the two diseases and treatments of the diseases are different. Colorectal cancer, for example, is primarily adenocarcinoma, and anal cancer is usually squamous cell carcinoma (SCC).

More women than men are diagnosed with anal cancer each year. In the US, about 5,530 women and 2,770 men are newly diagnosed with anal cancer annually. In the UK, annual anal cancer diagnoses are comprised of roughly 1,000 women and 480 men.

In the US, the risk of being diagnosed with anal cancer in one’s lifetime is about 1 in 500. This risk is slightly higher in women than in men. In the UK, one’s lifetime risk of bowel cancer is 6% for women and 7% for men. Anal cancer makes up about 2% of bowel cancers in the UK.

The average age at diagnosis in the US is 60. In the UK the peak is 65.

It is estimated that over 91% of anal cancer cases are caused by human papillomavirus (HPV).

Worldwide, HPV causes 5% of all cancer. In addition to anal cancer, HPV also causes cervical, vaginal, vulvar, penile and head and neck cancers.

If you are reading this, the chances are you or a loved one has experienced an anal cancer diagnosis. This diagnosis can bring with it more questions than answers. This fact page is intended to provide you with some of the key facts and figures about anal cancer. We encourage you to contact us with any questions or concerns. We are here for you.

Signs and Symptoms of Anal cancer

It is important for people who have anal cancer symptoms to be examined by their healthcare provider or referred to a specialist. Although these symptoms may indicate the presence of anal cancer, some individuals with anal cancer may be asymptomatic. This can happen when the disease is in its early stages.

As the disease progresses, anal cancer can present with certain signs and symptoms.

  • Anal or rectal discharge, such as pus, mucus or bleeding.
  • Rectal, anal or surrounding area pain, itching, pressure or a full feeling. These symptoms may be constant or exacerbated by bowel movements or sex.
  • Change in bowel frequency, size or difficulty. For example stools may become more narrow, you may experience increased straining, or you may use the bathroom more often.
  • A lump or hard area near the anus or swollen lymph nodes in the groin, pelvis or anal area.


Crissy-N-WR I thought I had a hemorrhoid. I remember driving to my sister’s house over Thanksgiving and trying to sit on one side because it felt like something was there. A week later, I had my annual OBG appointment and she performed a rectal exam. She assured me that it was NOT a hemorrhoid and that I should get it checked immediately.

Crissy – Stage II

London 16 (962x1280) I noticed that I was bleeding from my rectum in December 2010. I didn’t think much of it in the beginning. Assuming it was a case of hemorrhoids, I decided not to go to see the GP. The bleeding persisted and I noticed some changes in my bowel habits so eventually, after much persuasion from my family, I went to see my GP. I really believed that I was wasting the GP’s time, so was very taken aback when she said “I can feel an abnormality in your rectum, I need to refer you for further investigation”.

Sue D – Stage I

Peer to Peer Support Program

Looking for someone to talk to about your anal cancer diagnosis? We are here to help.

Anal Cancer Staging

Staging is used by doctors to describe how far a cancer has spread. Treatment options and outlook depend on a cancer’s stage.

There are four stages of anal cancer according to the National Cancer Institute:

  • Stage I: Cancer exists and the tumour is 2 centimetres (cm) or smaller.
  • Stage II: The tumour is larger than 2cm.
  • Stage IIIA: The tumour is of any size and has spread to the lymph nodes near the rectum or to nearby organs such as the vagina, bladder or urethra.
  • Stage IIIB: The tumour is of any size and may have spread to the lymph nodes in the rectum, pelvis, and/or groin, and possibly to nearby organs.
  • Stage IV: The tumour is of any size and may have spread to the lymph nodes or nearby organs and has also spread to distant parts of the body.

Anal Cancer Types

There are three types of anal cancer. Treatment options vary depending on the type of anal cancer.

  • Squamous cell carcinoma (SCC) starts in the outer lining of the anus. Approximately 90% of anal cancers are squamous cell carcinoma and result from HPV most of the time
  • Basal cell carcinoma is a skin cancer that occurs in the area around the anus. They account for only a very small number of anal cancers and are considered a type of squamous cell carcinoma.
  • Adenocarcinoma is either in the lining of the anus near the rectum or in the anal glands that produce mucous.
  • Malignant melanoma occurs in the cells of the skin of the anal lining responsible for pigment and makes up ≤2% of anal cancers. Malignant melanoma may also be called skin cancer.


Causes and Risk Factors for anal cancer

Anal cancer and precancer have several causes and risk factors. According to the World Health Organization, a risk factor may be ‘any attribute, characteristic or exposure of an individual that increases the likelihood of developing a disease or injury’.

I had an abnormal pap over 20 years before, had a cryosurgery.  I never dreamed that the HPV that caused me to have dysplasia on my cervix could result in cancer somewhere else, especially since I had normal pap smears every year after that. Eventually, I came across the Anal Cancer Foundation website by following links from several other websites. The stories of the Paulette and the Thrivers helped me feel less alone, and I felt so much in common with them.

Connie, Anal Cancer Thriver

Approximately 9,090 people will be diagnosed with anal cancer in the US and about 1,400 in the UK annually.

In almost all cases, anal cancer is caused by HPV, a virus that nearly every person has at some point in their life. The other risk factors on this page – immunosuppression, sexual activity, tobacco use, and older age – all may increase the chance that an HPV infection becomes cancerous. However, there are people who don’t have these additional risk factors who also develop anal cancer.


Human papillomavirus (HPV) is the most common sexually transmitted infection in the US and UK. HPV is a skin virus that can lead to anal, cervical, vulvar, vaginal, penile and head and neck cancers. It is transmitted through skin-to-skin contact. The virus enters the DNA of the cell and causes changes that limit the body’s ability to destroy the cell even though it is infected with a virus. The impact is that the cell replicates abnormally. This may lead to groups of cellular changes that can become precancer or cancer over time.

Nearly all adults will have HPV at some point in their lifetime. Frequently HPV goes away on its own, although for some it can remain dormant in the body for decades, causing cancers to surface later in life. A small percentage of HPV infections develop into cancer. It is important to note that our immune system finds HPV the vast majority of the time, with 90% of HPV resolving within two years. There are over 100 strains of the virus, some cause cancer and some cause warts. Most people don’t even know they’ve had it. Vaccines now exist to prevent HPV and the cancers it causes and are routinely recommended for children to prevent infection.

There are certain HPV-related conditions that make it more likely that you will develop anal cancer:

  • History of anal warts or anal precancer: men and women with anal warts or anal precancer are at increased risk of developing anal cancer because this history indicates an HPV infection. If the infection is persistent with recurrent lesions, it can lead to changes in the anal cells, which may eventually become cancer if left untreated.
  • History of other HPV-related cancer: women with a history of cervical, vulvar or vaginal cancer are at risk of developing anal cancer because these cancers are also caused by HPV, and the immune system has demonstrated difficulty in fighting the virus.

Find out more about HPV and preventing the infection with vaccination.


Having a weakened immune system can make the body more susceptible to developing an infection. This is also true for HPV, which can more easily develop into a persistent infection in these individuals. Individuals at increased risk of developing anal cancer include:

  • HIV-positive men and women.
  • Individuals with autoimmune disorders.
  • Transplant recipients and other individuals on immunosuppressive drugs.

I contacted a leading doctor in the anal cancer field, who graciously spoke with me on the phone and explained his work with HPV and anal cancer. He said I likely had HPV since the ‘70’s, that had remained dormant for years, and that in the presence of severe immune suppression, probably had become carcinogenic.



Any sexual contact, including manual stimulation, has the ability to expose you to HPV. It’s important to reiterate that nearly all adults will have HPV at some point in their lifetime.

While increasing exposure will increase your chance of contracting HPV, even a person with only one lifetime partner can be infected with HPV. Having multiple sex partners can increase your chance of developing anal cancer because it can increase your chance of being exposed to a carcinogenic strain of HPV.

People who engage in anal sex are at a higher risk of developing anal cancer because they are at a higher risk of skin-to-skin contact in the anal region and contracting an anal HPV infection. Because HPV is a skin virus that is transmitted very easily, anal intimacy is not necessary to contract anal HPV or to develop anal cancer.

In addition, men who are uncircumcised are at a higher risk of developing a persistent HPV infection.

Condom use is always recommended to prevent contracting an STD. However, condom use is not completely effective at preventing HPV transmission.


Smoking increases your chances of developing anal cancer as the carcinogens (cancer-causing chemicals) in tobacco can affect the entire body. There is evidence that smoking may decrease the immune system’s ability to fight HPV infection. Studies have also shown that current smokers are at a higher risk of developing anal cancer than former smokers and those who have never smoked at all.

For help quitting smoking:

Hand rejecting cigarettes

US – For help quitting visit the CDC website on smoking cessation

UK – For help quitting visit the NHS website on smoking cessation 


Most cases of anal cancer are diagnosed when an individual is older than 50 years old. This is because HPV takes time to alter the cells to develop into cancer. However, there are cases of people in their 20s and 30s developing anal cancer.

If you think you are at risk of anal cancer, or are concerned you may have symptoms, see a provider to answer your questions. Find out more about anal precancer and screening for it.


Treatment options for anal cancer vary depending on stage and type. The three treatment options for anal cancer include chemotherapy, radiation and surgery.


Chemotherapies are a class of drugs that kill cancer cells and prevent them from multiplying.

Learn more about chemotherapy treatment for anal cancer.


Radiation for anal cancer involves using an external beam of radiation that is directed towards the location of the cancer to shrink tumours and kill cancer cells.

Learn more about radiation treatment for anal cancer.


Surgery can be used for early-stage anal cancer when the tumour is extremely small and localised.

Learn more about surgery for anal cancer.


Utilize yearly examinations, annual check-ups, or other medical visits as occasions to talk to your provider about screening, and as opportunities for them to screen for anal cancer. Individuals with anal cancer risk factors should discuss screening with their providers. See our screening section for more information on options. If you think something is wrong, and you feel your doctor is not appropriately addressing your concerns, seek a second opinion.

Some doctors may misdiagnose anal cancer for hemorrhoids. If your hemorrhoids persist and do not disappear after treatment, speak to your doctor about a more detailed examination or ask for a referral to a specialist.

Please register for our newsletter to stay informed on the latest in anal cancer symptom management.

questions ANSWERED

How do I find a provider who screens for anal precancer?

Finding a provider who knows how to screen for anal precancer is a great step to learning more about your anal health. Locate a provider near you.

What is HPV and  what role does it play in anal cancer?

HPV (Human Papillomavirus) is a skin virus that is transmitted through intimate contact. HPV can be either low-risk or high-risk. High-risk strains may result in 6 different HPV-related cancers including anal cancer. Learn more about HPV and HPV-related cancers.

My loved onE has been diagnosed with anal cancer. How do I help?

Going through an anal cancer diagnosis with a loved one can be very difficult and you may not know where to start. We have a wide range of support resources for caregivers to help you during this time.

How do I find support?

It may be difficult to locate the necessary information and resources needed to go through an anal cancer diagnosis and treatment. Anal Cancer Foundation provides resources like our Peer to Peer Support Program and links to other helpful programs to help you navigate your diagnosis and treatments.

How do I manage anal cancer treatment side effects?

Treatment can bring on immediate side effects, long-term side effects, as well as late effects that occur long after treatment has concluded. Because of this, it is important to understand how treatment can affect your body and how best to manage the changes that occur. Find out more about the side effects of anal cancer treatment.

Do ACF volunteers help people at any cancer stage and/or post-treatment?

Yes, connections are available for anyone at any point in their cancer experience. From newly diagnosed, to in treatment, to post-treatment, to post post-treatment, anal cancer Thrivers and their Caregivers are in need of support. We seek to provide support at any stage of your cancer journey.

What issues do support seekers (thrivers and caregivers) discuss with volunteers? What kind of help can volunteers give?

The relationship between a support seeker and an ACF Volunteer is a natural, friendly mentorship that is supportive in nature. ACF Volunteers never dispense any medical advice or try to diagnose a medical problem. ACF Volunteers listen, question and help thrivers through their cancer journey by sharing their own experiences. Conversation topics might include:

  • What treatments and side effects feel like in the Volunteer’s experience
  • Tips on dealing with side effects
  • Pain issues
  • Stigma and social experiences relating to the diagnosis
  • Experience navigating the medical system
  • Support from family and friends

What communications methods do thrivers, caregivers and  ACF volunteers use?

Together an ACF Volunteer and Thriver or Caregiver decide the best method(s) of contact that works for both the support seeker and the Volunteer. Communication with a Volunteer is often a progression of comfort on both sides. Some examples include:

  • Telephone
  • Email
  • Text Messaging
  • Video Chat
  • Social Media (with both parties ensuring the messages are private)
  • In Person Face-to-Face

How long does it take for someone to get connected to an ACF volunteer?

Anal Cancer Foundation (“ACF”) recognizes there is an urgency for cancer patients (we call them “Thrivers”) and cancer caregivers (“Caregivers”) seeking support. Our goal is to find and match Thrivers and Caregivers with an ACF Volunteer within one week of completing registration.

More links and information on anal cancer

For the Newly Diagnosed

Living with the Side Effects of Anal Cancer Treatment

Recurrent and Advanced Anal Cancer

Questions to Ask Your Doctor

Facing an Anal Cancer Diagnosis

Anal Precancer


The information is presented as downloadable documents that you may add to your library of resources.

Anal Cancer

Anal Cancer: The Facts
Information on anal cancer, testing, and treatment.

Anal Cancer: Questions to Ask Your Doctor
Knowing the right questions to ask your doctor after a diagnosis can be tricky. The questions outlined in this document will help you develop a list of your own questions to better inform your anal cancer experience.

We’re here to empower thrivers and the anal cancer community. But we can’t do it without your support.

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