What Is Anal Cancer?

Anal cancer is a rare disease that is diagnosed when cancer is present in the anus, the last part of the digestive tract before leaving the body. This is the tube through which stool passes when having a bowel movement. It is separate from, though connected to, the rectum.

When the cells of the tissue of the anus become abnormal and grow uncontrollably, cancer develops.

This article will review how anal cancer differs from rectal cancer, as well as discuss the symptoms, causes, and treatment options.

Types of Anal Cancer

Each type of anal cancer is named for the type of tissue from which the cancer cells originate. These include:

• Squamous cell anal cancer (the most common type)
• Adenocarcinoma
• Basal cell carcinoma
• Melanoma

Anal vs. Rectal Cancer 

Anal cancer and rectal cancer are different. When cancer is diagnosed, it is very important to determine the location in which the abnormal cancer cells developed. This helps to determine the type and treatment that is required, as they may be different even though they are physically close to each other in the body.

The rectum is the last few inches of the large intestine. The anus is the tube between the rectum and the outside of the body, and it is surrounded by a sphincter, which helps the anus open and close to allow stool to pass through.

Symptoms

One of the first symptoms of anal cancer may be bleeding, found when stool passes through the anus. It may be present on the toilet paper when wiping after a bowel movement, or it may be found on the outside of the stool. Other symptoms that may be present with anal cancer include:

• Itching around the anal area
• Mass at the anus
• Change in size of stool
• Pain in the anus
• Loss of control of bowel movements
• Abnormal discharge from the anus
• Enlarged lymph nodes in the groin

Anal Cancer Statistics

It is estimated that almost 10,000 people will receive a diagnosis of anal cancer in a year. Although it is a rare disease, it has been increasing in frequency in recent years.

Risk factors associated with the development of anal cancer include:

• Increasing age: Average age at diagnosis is 60 years old
• Smoking cigarettes: Increases risk of anal cancer eight times over a non-smoker
• Human papillomavirus (HPV) infection
• Comprised immune system: Either due to immunosuppressant medications or from HIV infection
• Having many sexual partners
• History of anal sex

Causes

Cancer is caused when the DNA of the cells in the tissue mutates and starts growing abnormally. As these abnormal cells continue to grow, they form into a tumor.

The risk factors mentioned above have the potential to cause the DNA to become abnormal. The most common cause of anal cancer is having an HPV infection. 

HPV is a common virus that is easily spread through human contact. It has been found to be linked to the development of multiple cancers, not only anal cancer. These include cervical and vulvar cancer, penile cancer, and cancer of the throat.

Often HPV is eradicated by the body’s immune system, but in some cases it is not and leads to the development of cancer years later.

Diagnosis

The diagnosis of anal cancer is made in multiple steps. 

History and Physical

The initial step is taking a medical history and evaluating for any risk factors that may be present that increase the risk of anal cancer. A review of any symptoms that may be present is completed as well.

A physical exam allows the doctor to evaluate the area of concern and inspect for the presence of any abnormal findings. For anal cancer evaluation, an exam may take place in which the healthcare provider places a finger in the anus and rectum to feel for any lumps or masses and inspect for bleeding. Lymph nodes in the groin may be evaluated to see if they are enlarged.

Imaging and Other Testing

Imaging studies may be done to evaluate the location and possible spread of cancer. These may include:

• X-ray
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET)
• Ultrasound

A person with suspected anal cancer will likely be referred to a gastroenterologist for further testing. These tests, such as anoscopy or endoscopy, are done by using a scope with a camera at the end to look into the anus and rectum to visually inspect the area.

Biopsy

A biopsy (a small tissue sample shaved off from the tumor) will be taken of suspicious tissue to be evaluated under the microscope to look for the presence of cancer cells. If cancer is confirmed, these cancerous cells will be tested to see if HPV is present.

When the testing and biopsy are complete, a stage can be given to the anal cancer. Staging helps the oncologist determine the best treatment options and prognosis. Staging is determined by evaluating the size of the tumor, involvement of lymph nodes, and the presence of cancer in distant areas.

• Stage I: Tumor size is 2 cm or less and has not spread to lymph nodes or any other areas of the body. 
• Stage IIa: Tumor size is between 2 cm and 5 cm and has not spread to lymph nodes or other areas of the body.
• Stage IIb: Tumor is larger than 5 cm but has not spread to lymph nodes or other areas of the body. 
• Stage IIIa: Tumor size is less than 5 cm in size and has spread to nearby lymph nodes but not anywhere else in the body. 
• Stage IIIb: Tumor can be any size and is growing into the organs near it, but has not spread into lymph nodes or other areas of the body. 
• Stage IV: Tumor can be any size and has spread into distant areas of the body. 

Treatment

Treatment types typically consist of surgery, radiation, and chemotherapy, and can be used alone or in combination to treat anal cancer. The final treatment plan is developed based on the stage of the cancer. 

Surgery

During surgery, the tumor and some surrounding healthy tissue are removed. Sometimes during surgery, lymph nodes near the area are removed and tested for cancer.

It is possible that the type of surgery required may result in the need for a colostomy, or an opening on the abdomen where feces is emptied from the intestines into a bag outside of the body.

Surgery is rarely the initial treatment for anal cancer and is only used if chemotherapy and radiation fail to eliminate the cancer.

Radiation

During radiation, high-energy beams are used to kill cancer cells. Radiation is typically given multiple days a week for a few weeks, with the final schedule determined by the radiation oncologist.

Radiation may cause damage to the skin and tissues in the area around the anus, causing pain or difficulty with having a bowel movement.

Chemotherapy

Chemotherapy is the use of medications that work by destroying cancer cells. These medications are often given through infusion on a specific schedule and may be used in combination with radiation. Some chemotherapy medications may be given through oral pills.

Intimacy and Anal Cancer 

Before engaging in any sexual activity following treatment for anal cancer, it is important to consult your healthcare providers first, to ensure it is safe to do so.

Once cleared by the oncology team, it is possible to have an active sex life after treatment for anal cancer, however some things may be different. Sensations may be altered following surgery, or things such as a colostomy bag may make one feel insecure.

Having conversations about hesitations or self-consciousness with your partner is important. Working through these things together can help you safely return to an active sex life.

Prognosis

The prognosis for anal cancer can vary depending upon the stage at diagnosis. For an early-stage cancer that has not spread to lymph nodes or other areas of the body, the five-year survival rate is 82%. This means that 82% of people with early-stage anal cancer are alive at five years.

The prognosis declines as the stage increases, and for cancer that has spread to nearby lymph nodes or other nearby tissues, the five-year survival rate is 66%. Five-year survival is 34% in people with cancer that has become metastatic, or spread to other areas of the body.

Coping 

Many aspects involved with having anal cancer can lead to stress, anxiety, fear, or worry. From the physical changes that come with surgery or radiation, to the fear of chemotherapy side effects, a good support system is incredibly important to have to help you cope with the changes being faced.

Your healthcare team can be a valuable resource to rely on in coping with cancer. Ask them any questions that may come up. They can educate you along the journey to help you know what may be expected to happen or how to treat any side effects that develop.

Finding supportive family members or friends can also be important to have. This support system can be there to help with physical needs, such as making meals or running errands, and can be available for the emotional support that will be needed as well.

A Word From Verywell 

Receiving a diagnosis of anal cancer, or having a loved one with the diagnosis, can be a scary and uncertain time. An early diagnosis can come with long-term survival, but finding a good oncology team is important.

If you or your loved one has any symptoms, such as bleeding or pain in the anus, discuss them with your healthcare team to have these symptoms evaluated.