What is Cancer
Cancer Types

Anal Cancer

What is the anus?
The anus is the last 2 cm to 3 cm of the bowel and the muscular ‘ring' at the end of the rectum, which opens to allow solid waste (stools) to exit the body.
The lowest part of the anus is known as the anal margin. This area is made up of muscles called the anal sphincters. The external anal sphincter is the muscle that we use to control our bowel movements.
What is anal cancer?
Anal cancer is an uncommon cancer affecting the tissues of the anus.
Types of cancer
Most anal cancers are squamous cell cancers. Squamous cells are a type of cell that line the surface of the anal canal. There's also a rare type of anal cancer called adenocarcinoma of the anus. This is cancer of the cells that make the mucus that helps the stools (faeces) move smoothly out of the anus (called glandular cells).
How common is it ?
According to Dr Suresh Kumarasamy, the past president of the Obstetrical & Gynaecological Society of Malaysia and consultant gynaecological oncologist, anal cancer incidence is reported to be low in Malaysia as there is no routine screening advocated in the nation.
Risks and causes
A risk factor is anything that can increase your risk of developing a disease. Different cancers have different risk factors. However, even if you have one or more of the risk factors for a certain disease it doesn't mean you'll definitely get it.
We don't know the exact cause of anal cancer but there are several risk factors. They include diseases that are transmitted sexually, such as chlamydia, genital warts, human papilloma virus (HPV) and others. HIV/AIDS can also put people at higher risk.
Smoking has also been shown to increase the risk. Giving up smoking can decrease your risk of developing many types of cancers including anal cancer.
At first there may be no symptoms. Bleeding and discomfort in the area are common symptoms. Other symptoms include pain, itching, straining during a bowel movement, change in bowel habits, change in the diameter of the stool, discharge from the anus, and swollen lymph nodes in the anal or groin area.
If you have one of these symptoms it doesn't mean you have anal cancer. Remember that anal cancer is rare, and your symptom is likely to be caused by something less serious. But see your doctor if any symptoms persist for more than 2 weeks.
Your doctor will examine you and refer you for tests to see if you have cancer. This can be a worrying and tiring time, especially if you need to have several tests. If the tests show you have or may have cancer, your doctor will refer you to a specialist, who will examine you and may ask you to have more tests.
You may need a blood test to see if your red blood cells are low (anaemia). You may also need blood tests to check your liver and kidney function. You'll also need to have an examination and biopsy of your back passage (rectum). This is called proctoscopy or sigmoidoscopy. Both these tests involve having a long tube with a light on it inserted into the rectum. Your doctor will inflate your bowel with some air, which allows them to see more clearly. They may take a tissue sample (biopsy) to examine under a microscope for cancer cells. This procedure is usually done as an outpatient.
If your doctor needs to get a closer look and take more tissue samples you may have another examination under general anaesthetic. This can help your doctor stage your cancer.
You may have other tests such as a bone scan or CT scan if your doctor is concerned the cancer has spread to other parts of the body. Your doctor will explain the tests to you.
The test results will show whether you have cancer. They'll show where the primary cancer is and whether the cancer cells have spread to other parts of your body (this is known as metastasis). This helps your doctors ‘stage' the disease so they can work out the best treatment for you.
The staging system used for anal cancer is known as the ‘TNM system' (T=tumour, N=nodes, M=metastases).
  • T followed by a number between 1 and 4 describes how far the cancer has spread into the anal wall and nearby tissue. A higher number after the T (for example, T3 or T4) means it has spread further.
  • N plus a number from 0 to 3 describes whether the cancer has spread to lymph nodes near the anus and, if so, the amount of cancer in the nodes. Higher numbers are used for nodes that are more affected by the cancer.
  • M followed by 1 means the cancer has spread to other organs or to lymph nodes that are not near the anus. M0 means there is no sign of the cancer having spread in this way.
Doctors combine this information to work out the stage of the cancer, from Stage 1 (I) to Stage 4 (IV). For example, a cancer assessed as T1, N0, M0 (tumour contained within the anus, lymph nodes not affected and no metastasis) would be called a Stage I cancer.
The lower the ‘number' stage the less advanced the cancer is and the easier it will be to treat.
Ask your doctor to explain the stage of your cancer in a way you can understand. This will help you to choose the best treatment for your situation.
Written By:
Annie Angle, cancer nurse, Dip. Oncology Nursing, Royal Marsden, London.