What You Need To Know About Anal Cancer

Anal cancer can be classified based on the location where the cancer appears:

Anal canal cancer: The anal canal connects the rectum (the last part of the large intestine) to the outside of the body and carries feces out of the body. Cancer that occurs within this area is known as anal canal cancer.

Anal margin cancer: Cancer cells can also appear in the portion of skin around the opening of the anus, where the anal canal connects to the skin outside of the body. This is known as anal margin cancer.

Once cancer has started growing, it can spread into nearby tissues. Because of this, it's not always easy for doctors to tell where a particular individual's anal cancer originated from. For example, cancer that starts inside the anal canal can grow and spread to the anal margin.

A few different types of anal cancer are classified based on which type of cells they arise from.

Types of anal cancers

Squamous cell carcinoma

This is the most common type of anal cancer, accounting for about 90% of all cases. This cancer arises in squamous cells, which are flat cells that form most of the lining of the anal canal. Squamous cell carcinoma can occur either within the anal canal or at the anal margin.

There is a subtype of squamous cell carcinoma known as basaloid carcinoma or cloacogenic carcinoma. This is an aggressive form of anal cancer but is also relatively rare, making up only 1.6% of all cases of anal canal cancer.

Adenocarcinoma

This relatively rare type of cancer represents around 3–9% of cancerous growths in the anal canal. It arises in the cells that line the top part of the anal canal or in the glands that release mucus into the anus to lubricate it. They may also spread into the tissue around the rectum.

Melanoma

This is an aggressive but uncommon anal cancer. It forms in the pigment-producing cells of the skin.

Basal cell carcinoma

This type of skin cancer makes up less than 1% of anal cancer cases. It can be found in the skin around the anal margin, although it's far more common in areas regularly exposed to the sun, such as the hands. Basal cell carcinoma develops in small lesions.

The symptoms associated with anal cancer are often present in other conditions. The following are diseases that share similarities with this illness:

  • Chancroid

  • Anal fissure/fistula

  • Hemorrhoids

  • Condylomata acuminata (warts)

  • Psoriasis

Anal cancer is a type of cancer that occurs in the anal canal or at the end of this canal. This canal is at the end of the digestive tract. From this point, solid waste (poop) leaves the body.

The anal canal connects the rectum, the large intestine's last part, to the body's outside. Anal cancer should not be confused with colorectal cancer, which affects the colon (the large intestine) or the rectum. Anal cancer is far less common than colorectal cancer and requires different treatment types.

Statistics

Anal cancer is relatively rare. However, this disease has been on the rise in recent years. The American Cancer Society¹ estimates that there will be around 9,440 new cases of this disease in 2022. The disease is more common in women and affects about twice as many women as men.

Fortunately, anal cancer is treatable. In the United States, 69% of people with anal cancer will survive for at least five years. However, it can still be fatal. It's estimated that 1,670 people will die from anal cancer in the US in 2022.

Symptoms

There are several signs to look out for when identifying anal cancer¹. These include:

  • Bleeding from the anus or rectum

  • Lumps around the anus

  • Pain around the anal region, which may be worse when using the bathroom

  • Anal itching

  • Discharge from the anus

  • Diarrhea or constipation

  • Feeling like you need to pass solid waste (poop) very often

  • Weight loss

Other conditions of the digestive system can also cause similar symptoms. A doctor will need to evaluate you to determine the cause of your symptoms².

Causes

As with all types of cancer, we don't always know exactly what causes a particular person to get anal cancer¹.

However, there is a strong link between anal cancer and a virus known as human papillomavirus, or HPV. This virus can be transmitted via unprotected vaginal, anal, or oral sex. A woman infected with this virus in the genital or anal region increases her risk of cervical cancer. It also increases the risk of anal cancer in both men and women.

Other causes and risk factors for anal cancer² include:

HIV

Having HIV increases the risk of developing an HPV infection, which can lead to anal cancer. In addition, HIV decreases the function of the immune system. A healthy immune system can sometimes get rid of cancer cells before they develop into full-blown cancer, but in a person with HIV, the immune system can't do this. This leads to a higher risk of cancer in people with HIV, including anal cancer.

Smoking

Smoking is known to cause many types of cancer, including anal cancer. Certain chemicals in tobacco smoke can spread around the body and damage the DNA of cells, which causes them to become cancerous. These chemicals can also weaken the immune system, increasing HPV and anal cancer risk.

Weakened immune system

HIV is not the only factor that can weaken a person's immune system. People who have suppressed immune systems for any reason are at increased risk of anal cancer.

Gender

More women than men are likely to contract anal cancer. This is primarily due to the high rate of HPV in women. Women engaging in sex from an early age can increase the odds of HPV. Likewise, having an uncircumcised partner or multiple sexual partners can increase the risk of HPV.³

Race

There are differences in the rates of anal cancer in people of different races. The impact of race on the risk of anal cancer is complex, and the reasons for the disparities are not completely understood.

Hispanic men are less likely to develop anal cancer than other men. However, Hispanic women are at a higher risk than other women.

African-American men have a higher risk of developing anal cancer than Caucasian men. However, African-American women have a lower risk of anal cancer than Caucasian women.

Crohn’s disease

Crohn's disease causes inflammation of the digestive system. People with Crohn’s disease are at a higher risk of developing anal cancer because the inflammation can cause changes in the cell's DNA, leading to them becoming cancerous⁴.

Treatments

Anal cancer is curable. Treatment depends on the size of the tumor. Smaller tumors less than an inch across have a better chance of managing the growth.

If cancer has already spread to lymph nodes in the area, it will be harder to get rid of. As part of the diagnostic process, doctors will check whether this spread has occurred.

When treating anal cancer¹, the primary goal is to remove cancer. If possible, doctors will try to get rid of all of the cancer cells. If even one cancer cell is left behind, there's a chance that it will come back. However, it's also important to try to preserve the function of the anus as much as possible.

Some of the treatment options² for anal cancer include:

Surgical treatment

In cases where anal cancer is found at an early stage (meaning that it's fairly small and hasn't spread very far), it may be possible to use surgery to remove the tumor completely. The surgeon will also remove a small amount of healthy tissue surrounding the tumor to reduce the chances of the cancer growing back. It's important to preserve the sphincter muscles, which are ring-shaped that keep feces from leaking out of the anus.

Other treatments, including chemotherapy and radiation therapy, are usually used in more advanced cases instead of surgery. However, a more extensive surgical procedure may be used if these methods are ineffective. This is known as abdominoperineal resection. It involves removing the anus, rectum, and lower part of the colon. The surgeon creates a hole in the abdominal wall, called an ostomy, and connects the end of the colon to this hole. Afterward, pooping normally will be difficult. Instead, solid waste will pass out of the body and into a bag connected to the ostomy.

Chemotherapy

Chemotherapy uses medications to kill cancer cells or to stop them from multiplying and growing. Although it can be effective in treating cancer, chemotherapy also affects your body's healthy cells, causing serious side effects.

A combination of chemotherapy and radiation therapy is most commonly used for anal cancer that's too advanced to be treated with surgery. Chemotherapy can then be used before or after surgery for someone with early-stage cancer to help shrink the tumor. Chemotherapy after surgery can kill cancer cells that may already have spread away from the main tumor and decrease the chances that cancer will return.

Radiation therapy

This treatment uses the energy of radiation to kill cancer cells. For anal cancer, an approach called external beam radiation therapy is most often used. This involves directing radiation energy from outside the body onto the cancer cells. A more advanced version of this approach, known as intensity-modulated radiation therapy, can help minimize the amount of radiation that healthy cells are exposed to, so there are fewer side effects.

Much like chemotherapy, radiation therapy can be used as a main part of the treatment when surgery is not a good option. It can also be given before or after a tumor removal surgery.

Prevention

Anal cancer isn't always preventable, but there are ways to reduce your risk¹. These include:

HPV vaccine

There are vaccines available to decrease your risk of getting HPV. This will help decrease your risk of anal cancer, as well as cervical cancer (for women) and genital warts. If you haven't been vaccinated against HPV, then you may want to consider getting this vaccine.

Quitting smoking

Smoking is linked to many types of cancer, including anal cancer. Quitting smoking can reduce your risk. If you'd like help quitting, bring it up with your doctor. They can help to support you in this process.

Practicing safe sex

If you're sexually active outside of a mutually monogamous sexual relationship (a relationship where the two of you only have sex with each other), then you should use a condom every time you have any type of sex, whether vaginal, anal, or oral. While condoms aren't perfect, they can greatly decrease the chances of getting HPV and other sexually transmitted diseases.

  1. Can anal cancer be prevented? | American Cancer Society

Awareness

Although rare, anal cancer is a disease on the rise. Most people don't know much about this type of cancer.

March 21 is known as Anal Cancer Awareness Day¹. Today, some people share information about anal cancer and how to prevent it on social media. The Anal Cancer Foundation organizes a campaign to raise awareness for anal cancer.

  1. Anal cancer awareness day | Anal Cancer Foundation

Costs

In addition to being a serious ailment, anal cancer is often an expensive disease. One study¹ determined that people with anal cancer over age 66 spent an average of $50,150 in lifetime costs to manage anal cancer.

Treatment costs can vary from person to person. They depend on factors like the cancer stage and the specific treatments chosen. If treatments are needed to prevent cancer from coming back, this will add to the cost.

Doctors & specialists

You should tell your doctor immediately if you have any symptoms that might indicate anal cancer¹, you should tell your doctor right away. They may start by doing some tests to determine the cause of your symptoms.

You might be referred to a gastroenterologist, who is a doctor that specializes in diseases of the digestive system. You might also be referred to an oncologist, a doctor specializing in cancer. If you're having surgery, you may also be referred to a colorectal surgeon, who specializes in performing surgery of the colon, rectum, and anus, or to a surgical oncologist, who specializes in cancer surgery.


Clinical trials for anal cancer

Not yet open
The CanCope Study: Comparing the effects of Two Online Wellbeing Programs on the Mental Health of Cancer Survivors
VIC (AU)
Not yet open
Study of the use of MRI for radiation therapy treatment planning for patients with complex pelvic cancers
NSW, QLD, SA, VIC (AU)