What you need to know about anal cancer

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Common symptoms of anal cancer include:

• bleeding from the rectum
• itching around the rectum
• pain or a feeling of fullness around the anus
• lumps that may resemble hemorrhoids
• changes in bowel movements
• narrow stools
• a discharge from the anus
• swollen lymph nodes in the groin or anal area

Some of these symptoms can also be the result of hemorrhoids, anal warts, or anal tearing. However, a person should see a doctor if these changes occur, to rule out cancer.

Anal cancer develops when cells grow uncontrollably and form a tumor. Two types of cancer can form in the anus, depending on where the cancer starts.

Squamous cell cancer: The anal canal connects the rectum to the outside of the body. Squamous cells line the canal. These flat cells look like fish scales under the microscope. Most anal cancers are squamous cell carcinomas because they develop from squamous cells.

Adenocarcinoma: The point where the anal canal meets the rectum is called the transitional zone. It has squamous cells and glandular cells. Glandular cells produce mucus, which helps the stool pass through the anus smoothly. Adenocarcinoma can also develop from the glandular cells in the anus. Around 3–9% of anal cancers are of this type.

Risk factors

The risk factors for anal cancer include:

HPV: There is growing evidence that some types of HPV increase the risk of various cancers. Researchers have linked the presence of HPV16 to various cancers, including cervical cancer and some head and neck cancers.

Other cancers: People who have had another HPV-linked cancer seem to have a higher risk of anal cancer. For females, these include vaginal or cervical cancer, or a history of precancerous cells in the cervix. Males who have had penile cancer have a higher risk, also.

HIV: People with HIV have a higher risk of developing anal cancer than people without the virus.

Reduced immunity: People with a suppressed immune system have a higher risk. The immune system can be weaker in people with AIDS and those who take medications following a transplant.

How can people with a weak immune system stay healthy? Find out here.

Sexual activity: Having multiple sex partners can increase the risk, as this increases the chance of exposure to HPV.

Sex: Anal cancer is more common in females than in males. However, among African Americans, it is more common among males up to the age of 60 years, after which it is more likely to affect females.

Age: As people get older, their chances of developing anal cancer increase.

Smoking: Smokers have a significantly higher risk of several cancers, including anal cancer. Quitting may lower the risk.

The outlook for a person with anal cancer will depend to some extent on the stage at which they receive a diagnosis. Experts use statistics to work out how many people can expect to live another 5 years or more after a cancer diagnosis.

According to the ACS, the chances of living at least 5 years with anal cancer are:

• 82% for localized cancer, which has not spread beyond the original site.
• 64% for regional cancer, which has only spread to nearby tissues.
• 30% for distant cancer, which affects other areas or organs, for example, the liver.

Specialists have based these predictions on disease figures for 2008–2014. As medical knowledge and treatments improve, so should the outlook.

Other factors affecting the outlook include the individual’s overall health and age. However, anyone who receives a cancer diagnosis at an early stage will have a better chance of effective treatment than those whose diagnosis is later. For this reason, it is essential to see a doctor soon if changes occur in or around the anus.

It is often possible to detect anal cancer in the early stages, especially if it occurs in the lower part of the anal canal.

To diagnose anal cancer, a doctor will:

• ask the person about their symptoms
• take a medical history
• carry out a physical examination

If the doctor believes anal cancer may be present, they will refer the person to a colorectal surgeon, a doctor who specializes in bowel conditions.

The specialist may carry out a number of tests.

A rectal examination

The doctor may insert a proctoscope, anoscope, or sigmoidoscope into the anus to examine the area in more detail. This will help determine if the person needs a biopsy.

A biopsy

The doctor will take a small sample of tissue from the anal area and send it to the lab for examination under a microscope.

If the biopsy reveals cancerous tissue, the person will need further tests to find out how large the cancer is and whether it has spread.

A CT, MRI, or ultrasound scan can help confirm the results. This may include a rectal ultrasound, where the doctor inserts an instrument into the anus to be able to see the tissues more clearly.

What is a biopsy, and what does it involve? Learn more here.

To reduce the risk of anal cancer, a person can:

• have the HPV vaccination before they become sexually active
• use condoms when having sex
• avoid or quit smoking

People should seek medical advice for any changes that affect the anus, even if these give no suggestion of cancer.

An individual can also ask a doctor about screening if they have a high risk, such as HPV infection.

Anal cancer is a relatively rare cancer with close links to the HPV. Having the HPV vaccination and seeing the doctor about any changes in the anal area can help reduce the risk of anal cancer and its complications. People with a higher risk should consider asking their doctor about screening.