Anal Cancer: Signs And Symptoms To Watch For

Do you or a loved one suspect that you might have anal cancer but are unsure of the main signs?

Determining if you are affected by this relatively rare type of cancer can be a challenge, especially since there are a number of common conditions that might mimic anal cancer symptoms, such as hemorrhoids, anal warts, and anal fissures.

To help you determine if you should get in touch with your doctor for consultation and testing, we've put together the main signs and symptoms of anal cancer for you to watch out for.

You'll also learn about the different types of anal cancer, their main causes and risk factors, screening recommendations and diagnostic tools, and the key treatment and preventative options for the condition.

Our goal is to give you peace of mind by providing important information about anal cancer that can help you better understand, prevent, and manage the disease.

What is anal cancer?

Anal cancer forms when cancer cells start multiplying in the tissues of the anus, which is the opening at the end of your gastrointestinal (GI) tract used to dispel fecal matter from your body.

Although it's much rarer than colorectal cancer, the American Cancer Society estimates that there will be 9,440 cases of anal cancer diagnosed in 2022, and new cases have been rising in recent years.¹

It's slow-growing cancer, and usually, when it spreads, the liver is affected first. Like most cancers, it includes a pre-cancerous stage and four cancer stages (stages 0, stage I, stage II, stage II, and stage IV) that pinpoint how localized or advanced the spread is in your body.

Anal cancer differs significantly from colon and rectal cancers in its causes and main risk factors, even though all three cancers form along your GI tract. Likewise, some of the key symptoms of anal cancer are unique, although others match those of rectal cancer.

Let's begin by taking a look at the main anal cancer symptoms.

Symptoms

What are the symptoms of anal cancer?

Cancer Research UK estimates that about 20% of people diagnosed with anal cancer have no symptoms. For those who do, the main signs to look out for include blood in your stool and rectal bleeding.²

Other key signs of anal cancer include:

• Pain in the rectal region

• A lump or lumps in the anus

• Changes in bowel habits, such as feeling like you "need to go" more often

• A feeling of expansion or fullness in the anus

• Ribbon-like stool

• Itching that continuously reoccurs

• A mucous discharge of the anus

Anal cancer symptoms vs. colorectal cancer symptoms vs. hemorrhoids

Certain signs of rectum cancer and colon cancer might mimic those of anal cancer, including rectal bleeding, bloody stool, narrower bowel movements, and changes in bowel habits.

The key difference between these potential anal, colon, and rectum cancer symptoms and hemorrhoid symptoms is that they tend to be persistent and worsen over time, whereas hemorrhoid symptoms tend to come and go.

If you think you may have GI tract cancer, it's recommended to see a healthcare practitioner right away, as early detection helps increase your chances of successful treatment.

Types of anal cancer

There are six main types of anal cancer recognized by the American Cancer Society. They fall into two main categories: cancers of the anal canal (above the anal verge) and cancers of the anal margin (below the anal verge). The anal verge connects your anal canal to the skin outside your anus.  

Precancers (also known as 'dysplasia')

This is when the cells of the anal lining are not yet cancerous, but they may look abnormal when examined under a microscope. For instance, certain warts have areas of dysplasia (or abnormal growth).

Most common anal cancer

Squamous cell carcinoma

Flat cells found in the surface and sometimes middle layers of the skin and tissue linings of cavities are known as squamous cells. Squamous cell cancers are the most common type of cancer that can spread (metastasize). They can occur in both the anal canal and the anal margin.³

Rare anal cancers

Adenocarcinoma

Adenocarcinomas are cancers that start in sweat glands of the skin called apocrine glands, in cells at the upper region of the anus near the rectum, or in glands that secrete mucous into the anal canal. Apocrine gland carcinoma is treated like anal cancer, whereas the other types of adenocarcinomas may be treated like rectal cancer.

Melanoma

Cells that create brown pigments are called melanin and might be located in the anal canal or anal margin. Since they can be difficult to see due to their darker color, many anal melanomas are found at later stages, although they are rare among anal cancers.

Gastrointestinal stromal tumor (GIST)

Although GIST is one of the most common GI tumors, it's only rarely found in the anal canal itself. When these tumors do appear there, they tend to recur in this local area at high rates. Therefore, treatment may include multiple therapies in order to help ensure successful treatment outcomes.

Basal cell carcinoma

Basal cells sit in the lower layers of the outer layer of the tissue and skin. Like GIST, anal basal cell carcinoma is rare. Referred to officially as 'perianal basal cell carcinoma,' it's more likely to develop when squamous cell carcinoma is present or if the anus is inflamed or injured.⁴

Note: Certain tumors, warts, skin tags, and polyps can also develop in the anal margin or anal canal and be benign (noncancerous).

What is the most common type of anal cancer?

Squamous cell carcinoma is, by far, the most common type of anal cancer. It affects about 90% of people diagnosed with anal cancer.

Causes & risk factors

How do you get anal cancer?

While there's no definitive cause of anal cancer, about 90% of diagnoses are linked to infection with the human papillomavirus (HPV).⁵

That being said, exposure to more than 150 HPV subtypes rarely causes anal cancer. However, a certain subtype called HPV-16 does infect many people who develop squamous cell carcinomas, and HPV-18 is also sometimes present. 

The HPV proteins can stop two proteins that help prevent the development of cancer from doing their job of keeping cell growth in check, causing cancer cells to grow out of control.

One of the main risk factors for catching HPV is lowered immunity. That's why those with HIV are at a particularly high risk of developing anal cancer. Other risk factors include:

• Sexual activity that can spread HPV (or HIV)

• Anal warts

• The presence of other types of cancer, especially cervical, vaginal, and vulvar cancers

• Lowered immunity from disease or other factors

• Smoking

Smoking tobacco products has been shown to increase recurrence rates of squamous cell cancer of the anus and decrease survival rates. The American Cancer Society recommends quitting smoking if you are diagnosed with this or any other type of cancer.⁶

Due to its harmful effects on most parts of the body, quitting smoking is recommended regardless of your risk of cancer.

Who gets anal cancer?

Anal cancer is rare. Only about 0.2% of men and women will be diagnosed with anal cancer during their lifetime, and just under 75,000 people live with the disease in the United States today.⁷

It's just slightly more common in women than men, although age is a much higher risk factor than gender, with over 80% of cases diagnosed in people aged 55 and older.

Diagnosis

Screening for anal cancer

Screening for anal cancer is done for early detection of the disease if you don’t have any signs or symptoms. Anal Pap smears, also known as anal Pap tests or 'anal cytology' tests, are the screening test of choice for anal cancer. Analysis of the Pap smear is done to check for any cell irregularities that may indicate that you have cancer.⁸

It's recommended you get screened for the condition if you have any of the early warning signs or risk factors, especially if you are a woman aged 45 or older diagnosed with HPV-16. Early screening is so important because, while only 45.3% of these types of cancer are diagnosed at the local stage (before they've spread), the relative survival rate is 83.3% for local anal cancer.

How is anal cancer diagnosed?

To find out if you have anal cancer, your doctor will begin by taking a full medical history. They will then perform a rectal exam to feel for any lumps or signs of an anal tumor that might be present. This can be done as part of a regular pelvic exam for women or during a prostate exam for men.

It's known as a digital rectal exam (DRE), and your doctor inserts a lubricated, gloved finger in your rectum to perform the assessment. Irregularities or growths that might appear abnormal can also be seen when your doctor examines the anus.⁹

In addition, irregularities may be found using an anal Pap smear (anal cytology) test during screening. If there are irregularities in your anal Pap smear or DRE, the next step would be to biopsy a tissue sample in a lab to confirm if the cells are cancerous.

To collect the sample, often your doctor (or a specialist) will use a tool called an anoscope, which is a short tube with a light on the end that's inserted into your anus, usually while you're awake. The procedure may be a little uncomfortable, but it isn't painful.

If need be, an endoscopy may also be performed. This involves a flexible device with a camera on the end being inserted into your anus to help your doctor better examine your canal for signs of cancer.

Other possible tests to help diagnose and treat your anal cancer include:

• Imaging tests, like ultrasound, to help pinpoint cancer and determine if it has spread

• Computed tomography (CT) scans (AKA virtual colonoscopies) to create cross-sectional images that determine if the lymph nodes and other organs are affected by cancer

• Sigmoidoscopy to examine the rectum

• An HIV test to ensure proper treatment protocols are in place for those who may be HIV positive before cancer treatment begins

Treatment

How is anal cancer treated?

The most common treatment option for anal cancer is chemoradiation. Doctors will often use lower-dose chemotherapy combined with radiation to help reduce this treatment's side effects.¹⁰

Surgery is also performed to remove cancerous anal tumors. “Local resections” are the main surgery used today, where the surgeon removes only the tumor and a small amount of tissue around it. Although much less common, abdominoperineal resection (APR) to remove certain GI tract organs may also be performed if cancer returns or spreads.

New anal cancer treatment options are also being used now, thanks to clinical trials, such as laser therapy. Specifically, a technique called photodynamic therapy employs a combination of drugs called photosensitizing agents that are absorbed by cancer cells and light therapy.¹¹

When light at certain wavelengths is used on the cancer cells that have absorbed the photosensitizing agents, special oxygen molecules are formed that target and kill cancer cells. The light also may work to cut off the blood vessels that are food sources for these cancer cells.

Immunotherapy drugs like Opdivo® (nivolumab) and Keytruda® (pembrolizumab) also show promise in treating anal cancer. These immunosuppressive drugs work by targeting certain immune receptor cells that fight against cancer cells. Other types of immunotherapy for cancer include monoclonal antibodies and cytokines that assist the immune system in attacking cancer.

Is anal cancer curable?

Anal cancer spreads slowly, and with early treatment, most people are free of cancer after five years. The overall five-year cancer survival rate for anal cancer is almost 69%. Even when it has spread to nearby tissue and lymph nodes, the survival rate is 66%.¹²

Prevention

Can anal cancer be prevented?

Since the exact cause of anal cancer is still under investigation, it's not possible to completely prevent it. However, there are a few key medical interventions that can help you reduce your risk of contracting the disease, including:

• HPV vaccines, which help protect against HPV-16 and HPV-18. This vaccine is useful for both men and women to get.

• Properly treating HIV or other conditions that suppress the immune system

• Using condoms during sexual activity to help reduce the spread of HPV

• Quitting smoking

The lowdown

Knowing the signs and symptoms of anal cancer can help give you peace of mind and a better understanding of when to seek treatment. These signs include blood in the stool, rectal bleeding, changes in bowel habits, and pain, itching, or lumps in the rectal region. 

While the disease is rare, HPV infection is the major risk factor, and an HIV infection or a compromised immune system can increase your chances of contracting this virus.

Examination by a doctor, anal pap smears, biopsies using anoscopes, imaging tests, and colonoscopies are all used to diagnose anal cancer. 

Treatment includes chemoradiation, surgery, laser therapy, and immunotherapy. HPV vaccines and quitting smoking can also help reduce your risk of contracting anal cancer. With proper treatment, most people diagnosed with the condition are cancer free within five years.

Frequently asked questions

How common is anal cancer?

Anal cancer is very rare and only affects about 0.2% of the population.

How fast does anal cancer grow?

Anal cancer is very slow-growing, and most people are cancer free after five years when they seek medical treatment.

What does anal cancer feel like?

Anal cancer may be very painful, and you may feel like there's a fullness in your anal region. However, about 20% of people diagnosed don't experience any symptoms at all.

What are the signs of anal cancer?

Rectal bleeding, blood in the stool, narrower bowel movements, a lump or lumps in the anus, anal mucous discharge, a feeling of fullness in the anus, rectal pain, recurrent itching, and changes in bowel habits are all anal cancer symptoms.

How do I know if I have hemorrhoids or cancer?

Hemorrhoids tend to flare up and then go away. Cancer symptoms (including anal cancer symptoms) are persistent and tend to worsen over time. It is always best to see your doctor if you have symptoms rather than assuming it is hemorrhoids

What causes anal cancer?

HPV is the main underlying factor for developing anal cancer. Smoking, lowered immunity, certain types of cancer, and HIV also increase your risk of developing the disease.