Anal Cancer
Diagnosis and Staging

This page covers tests that are often used to help diagnose and stage anal cancer.
Depending on the symptoms you have, you may also be asked to undergo other tests and investigations.

“My cancer scare changed my life. I’m grateful for every new, healthy day I have. It has helped me prioritize my life.” 

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Diagnostic Tests to Determine Cancer Type

Once the doctor is sure of an abnormality, a biopsy is done to determine further details about the type of cancer present.

Endorectal Ultrasound

What to expect

An endorectal ultrasound (EUS) is used to examine the lining of the anal canal and rectum from the inside. During the procedure, your doctor will insert a thin, flexible tube into your rectum, in order to examine your anal canal and surrounding structures for any tissues that could be cancerous. You can expect some minor pain or discomfort while undergoing the procedure. It is important that you choose a doctor and clinical team that you are comfortable with to perform your procedure. 

Prior to the procedure, you will need to ensure that your anal canal is empty. Any residue may obscure the view of the anal canal, rectum and surrounding areas during the exam. In order to ensure that the anal canal is empty, your doctor may ask you to

  • Refrain from taking solid foods the day before the procedure
  • Have clear liquids (such as plain water, black tea or black coffee or juices)
  • Stop taking food and liquids the night before the procedure
  • Take a laxative
  • Have an enema

It is important that you follow the instructions given by your doctor in order to ensure a successful procedure. Be sure to inform your doctor prior to the procedure if

  • You are pregnant or breastfeeding
  • You have previously had an allergic reaction to sedatives
  • You are taking any vitamins, supplements, ayurvedic medicines or homeopathic medicines

During an EUS

  • You may be asked remove your clothing (including undergarments) and change into a hospital gown. You may also be asked to empty your bladder.
  • You may be given a mild sedative or pain medication, either in a pill form or through an IV, to minimize discomfort during the procedure.
  • You will then be asked to lie on your side on the examination table, usually with your knees drawn towards your chest.
  • Try to relax, as this will make the procedure more comfortable for you.
  • Next, the doctor will insert the endoscope into your rectum. The endoscope is a long, flexible tube. It has a small ultrasound device (called a transducer), which produces sound waves to create a precise image of your anal canal and the surrounding tissue.
  • When the scope is moved, you may feel mild abdominal cramping, or you may have the urge to have a bowel movement.
  • If any abnormal areas are seen, your doctor may recommend that a biopsy be done.
  • The procedure will usually take 30 minutes to an hour to complete.
  • After the procedure, you may receive special instructions regarding the sedative. For example, your doctor may keep you under observation while you recover, to ensure that you do not have an allergic reaction. You may also be told to temporarily follow a special diet.
  • You may feel a cramping pain and experience light bleeding after the procedure. If you experience excessive bleeding or persistent abdominal pain, inform your doctor immediately.

Biopsy

What to expect

Biopsy involves the removal of a sample of cells or tissues from the anal canal for laboratory testing and is the only definitive method to diagnose anal cancer. It is a way to evaluate a suspicious area in your anal canal or rectum to determine whether it is cancerous.

Typically, biopsies will be done along with the endorectal ultrasound (EUS). It is important that you choose a doctor and clinical team that you are comfortable with to perform your procedure.

The fine-needle aspiration (FNA) biopsy is generally used for anal cancer. This is a quick, simple test in which a thin needle is used to remove tissue or fluid for examination under a microscope.

For a few days after the biopsy, your pelvic and rectal areas may feel sore and bruised. Don’t hesitate to talk to your clinical team about pain medication if you feel you might need it. The pain and bruising will generally subside in a couple of weeks. If it persists, please contact your doctor immediately.

Diagnostic Tests to Determine
Stage and Spread of Cancer

CT Scan

What to expect

A CT (computerized tomography) scan is an imaging study and is generally painless. It uses X-rays to take multiple images of the body from different angles to recreate three-dimensional pictures of your internal organs on a computer. It is important that you choose a doctor and clinical team that you are comfortable with to perform your CT scan.

You may be asked to refrain from eating or drinking for a few hours before your scan. Be sure to inform your doctor prior to your scan if

You are pregnant or breastfeeding

You have any metal or electronic
devices implanted in your body (such
as a pacemaker or metal pins)

You are afraid of enclosed spaces
(claustrophobic)

You have previously had an allergic
reaction to contrast material

You are taking any vitamins, ayurvedic
medicines or homeopathic medicines

During a CT scan

You may be asked to change into a hospital gown and remove your jewellery, watch, body piercings or any other accessory that contains metal. You may also be asked to empty your bladder.

You may be given a special dye (called contrast material) which can help highlight the areas of your body that are being examined. The dye can be given to you by mouth (in a drink), by injection through a vein in your arm or by an enema in your rectum. You may need to wait for 30 minutes to an hour for your body to absorb the dye.

Next, a nurse or technician will take you to the room which contains the CT scanner. You will be asked to lie on a narrow, motorized table that will slide you into the machine. The nursing staff may use straps to keep you in position. You can ask for a pillow if you are feeling uncomfortable. You will be asked to remain still for the duration of the scan.

As the table moves you into the CT scanner, various detectors and X-ray tubes will rotate around you. Each rotation will produce several cross-section images of your body. You may hear some buzzing or whirring noises – try not to be alarmed and remember to stay still.

The technicians will be seated in a separate room, but they will be able to see and hear you. You may be asked to communicate with them via intercom. They may ask you to hold your breath at certain times to improve image quality.

The scan will usually take 20-30 minutes to complete.

After the scan, you may receive special instructions regarding the contrast material. For example, your technician or doctor may ask you to wait for a few minutes to ensure that you do not have an allergic reaction. You may also be told to drink plenty of fluids to help your kidneys to flush out the contrast material through your urine.

PET Scan

What to expect

PET (Positron emission tomography) scan is a process that uses radioactive glucose to detect malignant tumour cells in the body. Malignant tumour cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. The scan is generally painless. It is important that you choose a doctor and clinical team that you are comfortable with to perform your PET scan. Some hospitals have a combined PET/CT scanner.

You may be asked to refrain from eating or drinking for a few hours before your scan. Be sure to inform your doctor prior to your scan if:

You are pregnant or breastfeeding

You have any metal or electronic
devices implanted in your body (such
as a pacemaker or metal pins)

You are afraid of enclosed spaces
(claustrophobic)

You have previously had an allergic
reaction to contrast material

You are taking any vitamins, ayurvedic
medicines or homeopathic medicines

During a PET scan:

You may be asked to change into a hospital gown and remove your jewellery, watch, body piercings or any other accessory that contains metal. You may also be asked to empty your bladder.

You may be given a special dye (called contrast material) which can help highlight the areas of your body that are being examined. The dye can be given to you by mouth (in a drink), by injection through a vein in your arm or by an enema in your rectum. You may need to wait for 30 minutes to an hour for your body to absorb the dye.

Next, a nurse or technician will take you to the room which contains the PET scanner. You will be asked to lie on a narrow, motorized table that will slide you into the scanner. The nursing staff may use straps to keep you in position. You can ask for a pillow if you are feeling uncomfortable. You will be asked to remain still for the duration of the scan.

As the table moves you into the PET scanner, the machine will begin to rotate around you. Each rotation will produce several cross-section images of your body. You may hear some buzzing or whirring noises – try not to be alarmed and remember to stay still.

The technicians will be seated in a separate room, but they will be able to see and hear you. You may be asked to communicate with them via intercom.

The scan will usually take about 30 minutes to an hour to complete.

After the scan, you may receive special instructions regarding the contrast material. For example, your technician or doctor may ask you to wait for a few minutes to ensure that you do not have an allergic reaction. You may also be told to drink plenty of fluids to help your kidneys to flush out the contrast material through your urine.

MRI Scan

What to expect

Magnetic resonance imaging (MRI) scan is a procedure in which an MRI scanner uses a high-powered magnet and a computer for comprehensive images of the internal organs and surrounding structures. MRI scans normally add supplementary information about anomalies in the stomach and may be recommended only in select cases. The scan is generally painless. It is important that you choose a doctor and clinical team that you are comfortable with to perform your MRI scan.

You may be asked to refrain from eating or drinking for a few hours before your scan. Be sure to inform your doctor prior to your scan if:

You are pregnant or breastfeeding

You have any metal or electronic
devices implanted in your body (such
as a pacemaker or metal pins)

You are afraid of enclosed spaces
(claustrophobic)

You have previously had an allergic
reaction to contrast material

You are taking any vitamins, ayurvedic
medicines or homeopathic medicines

During a MRI scan:

You may be asked to change into a hospital gown and remove your jewellery, watch, body piercings or any other accessory that contains metal. You may also be asked to empty your bladder.

You may be given a special dye (called contrast material) which can help highlight the areas of your body that are being examined. The dye is typically administered by injection through a vein in your arm. You may need to wait for 30 minutes to an hour for your body to absorb the dye.

Next, a nurse or technician will take you to the room which contains the MRI machine. You will be asked to lie on a narrow, motorized table that will slide you into the machine. The nursing staff may use straps to keep you in position. You can ask for a pillow if you are feeling uncomfortable. You will be asked to remain still for the duration of the scan.

As the table moves you into the MRI machine, the machine creates a strong magnetic field around you and radio waves are directed at your body. You may hear repetitive noises such as thumping or tapping – try not to be alarmed and remember to stay still. You can request earplugs or have music playing to help you block out the noise.

The technicians will be seated in a separate room, but they will be able to see and hear you. You may be asked to communicate with them via intercom.

The scan will usually take about 30 minutes to an hour to complete.

After the scan, you may receive special instructions regarding the contrast material. For example, your technician or doctor may ask you to wait for a few minutes to ensure that you do not have an allergic reaction. You may also be told to drink plenty of fluids to help your kidneys to flush out the contrast material through your urine.
How anal cancer is staged

The results of your diagnostic tests will help your doctor determine the size and position of the cancer, and whether it has spread. This is called staging. Knowing the stage and grade of your cancer will help your doctor plan the best course of treatment for you.

There are different systems for describing the stage of anal cancer.

THE TNM STAGING SYSTEM

The TNM staging system gives the complete stage of the cancer

T describes how far the tumour has grown into the anal canal.

N describes whether the cancer has spread to the lymph nodes and which nodes are involved. For example, N0 means no lymph nodes are affected. N1 means there are cancer cells in 1 to 3 of the lymph nodes.

M describes whether the cancer has spread to another part of the body. For example, M0 means the cancer has not spread (metastasised) to other parts of the body.

Sometimes the final TNM staging may not be certain until surgery is completed, since the tissue samples removed during the procedure will need to be analysed further.

THE NUMBER STAGING SYSTEM

Anal cancer can also be divided into five number stages.

Stage 0 is when abnormal cells have formed in the innermost layer of the anus. These abnormal cells may become cancerous and spread to the nearby tissues. Stage 0 is also called high-grade squamous intraepithelial lesion (HSIL).

Stage I is when cancerous cells have formed in the innermost lining of the anus. The tumour is 2cm or smaller.

Stage II anal cancer is further divided into stages IIA and IIB, depending on where the cancer has spread. In stage IIA, the tumour is larger than 2cm but not larger than 5cm. In stage IIB, the tumour is larger than 5cm.

Stage III anal cancer is sometimes called locally advanced anal cancer. It is further divided into stages IIIA, IIIB or IIIC, depending on where the cancer has spread. In stage IIIA, the tumour is 5cm or smaller and has spread to the lymph nodes near the anus or groin. In stage IIIB, the tumour is any size and has spread to nearby organs, such as the urethra or bladder, but has not spread to the lymph nodes. In stage IIIC, the tumour is any size and has spread to nearby organs, such as the urethra or bladder, as well as lymph nodes near the anus or groin.

Stage IV anal cancer is also called secondary or metastatic anal cancer. At this stage, the cancer has spread into the lymph nodes or other parts of the body, such as the liver or lungs.

GRADING

The grade of a cancer gives an idea of how slowly or quickly it might grow. The grade is based on how the cancer cells look under a microscope when they are compared with normal cells.

Grade 1 (low grade cancer)
The cancer cells look similar to normal cells (they are well differentiated). They usually grow slowly. These cancer cells are less likely to spread.

Grade 2 (moderate or intermediate-grade cancer)
The cancer cells look more abnormal and grow slightly faster than grade 1 cells.

Grade 3 (high-grade cancer)
The cancer cells look very different from normal cells (they are poorly differentiated). They may grow more quickly than grade 1 or 2 cells.

Treatment options for Anal cancer

The decision about the best course of treatment is based on these test results and the type, stage, grade and size of your tumour. Treatments like surgery, chemotherapy and radiation therapy are some of the options used for anal cancer. Refer to this section to understand the types of cancer treatments for anal cancer and possible side effects. Read more

Your cancer journey

Everyone deals with a breast cancer diagnosis and treatment in a different way. Refer to this section to
understand various aspects of your cancer journey and the road to recovery. Read more

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