Types of surgery for anal cancer

There are different types of surgery you might have for anal cancer. 

Some people may have surgery before they start chemoradiotherapy. Or just to remove the area containing the cancer cells (local excision). Others may need a large operation to remove their anus, back passage (rectum) and the last part of the large bowel (colon).

When do you have surgery for anal cancer?

A combination of chemotherapy and radiotherapy (chemoradiotherapy) is normally the main treatment for anal cancer. But you may have surgery:

• if you have a small stage 1 cancer in the anal margin
• if you’ve had chemoradiotherapy but it didn’t get rid of all the cancer or the cancer has come back after treatment
• if you can’t have chemoradiotherapy
• before chemoradiotherapy if you have symptoms such as pain, not being able to hold your poo (faecal incontinence) or an anal fistula

Your surgeon will explain if you need surgery and the type they recommend.

Small stage 1 cancer in the anal margin

Stage 1 anal cancer means the cancer is 2cm or smaller. And it hasn't spread to any nearby tissue, lymph nodes  or other organs. 

Your surgeon might recommend an operation to remove the cancer and a small area of healthy tissue around it. This is called a local excision. You may have this as your main treatment if the cancer is all of the following:

• smaller than 1cm
• in the anal margin
• doesn’t involve the muscles in your anus (sphincter muscles)

If chemoradiotherapy didn’t get rid of all the cancer or the cancer has come back

You might need surgery to remove your anus, rectum and last part of your colon. Doctors call this operation an abdominoperineal resection (APR) or an abdominoperineal excision of rectum (APER).

If the cancer has spread to nearby organs and muscles, your surgeon may also recommend removing them.

If you can’t have chemoradiotherapy

A small number of people might have an abdominoperineal resection as their first treatment. This may be if they have:

• had previous radiotherapy to the area between their hips (pelvis) and they cannot have more radiotherapy to cure the cancer
• have a type of anal cancer called adenocarcinoma  or adenosquamous carcinoma, which doesn’t respond as well to radiotherapy
• are having drugs to suppress their immune system  after an organ transplant – this is because they might not be fit enough to complete chemoradiotherapy without taking any breaks
• decided against having chemoradiotherapy

They usually have surgery instead of chemoradiotherapy.

Before chemoradiotherapy

Some people may need to have an operation before they start chemoradiotherapy. 

Colostomy

A colostomy is a type of stoma where your surgeon brings your large bowel out onto the surface of your tummy (abdomen). Poo passes out of your body through the colostomy and into a special bag that you stick to your abdomen.

Your surgeon may recommend a colostomy before you start chemoradiotherapy. This can be if you have symptoms such as:

• pain
• faecal incontinence
• a fistula between the anus and vagina

This is normally a permanent colostomy so you have it for the rest of your life.

Seton suture

If you have a fistula between your anus and the surrounding skin, it can cause an infection when you have chemoradiotherapy.

Your surgeon normally recommends an operation before you start treatment. They put a special thread called a seton suture through the hole made by the fistula. This works like a wound drain and helps the fistula to heal.

Your surgeon changes the seton suture every 6 months. But you normally have one in place until any changes caused by the radiotherapy have settled. This maybe up to a year and a half after treatment.

Local excision for anal cancer

Your surgeon removes the cancer and an area of healthy tissue around it. They leave the sphincter muscles intact so you can still control your bowels.

Your anaesthetist normally gives you a general anaesthetic for this operation. But some people have an injection in their back to numb their lower body instead. This is called a spinal anaesthetic.

You may be able to go home later the same day.

Abdominoperineal resection for anal cancer

This is a very large operation where your surgeon removes:

• your anus
• your rectum
• your lower colon
• some of the lymph nodes near your anus

After having surgery, you will no longer be able to poo as normal. So during the operation, your surgeon will make a permanent colostomy.

If the cancer has spread nearby, they may also remove:

• one of the muscles in your pelvis
• your bladder
• the prostate in men
• the womb , ovaries and all or part of the vagina in women

Before the operation, your surgeon and anaesthetist make sure you are well enough for the surgery.

How you have an abdominoperineal resection

Your surgeon will operate on both your abdomen and around your anus. This is all part of the same operation.

They operate on your abdomen to help them remove your lower colon and rectum. Your surgeon may do this part of the operation as:

• open surgery
• keyhole (laparoscopic) surgery
• robotic surgery

They also make a wound around your anus. And remove your anus, rectum and the lower part of your colon through this wound. This part of the operation is open surgery.

Before the operation, your surgeon talks with you about the risks and benefits of the type of surgery they recommend.

Open surgery

This means your surgeon makes longer cuts in the skin on your abdomen and around your anus. They operate through these cuts.

Keyhole surgery

Your surgeon makes a number of small cuts in your abdomen. This is instead of the larger cut that you have with open surgery.

Your surgeon passes a long, narrow tube called a laparoscope through one of the cuts. This connects to a camera and shows pictures of the inside of your body on a television screen. They also put some gas into your abdomen which creates space and helps them to see better. Your surgeon uses the other small cuts for the instruments they need to do the operation.

Keyhole surgery seems to be as good as open surgery at getting rid of the cancer. But the operation can take longer. And sometimes your surgeon may have to switch to open surgery during the operation.

In general, people who have keyhole surgery may have:

• less pain
• less blood loss
• leave hospital sooner
• fewer wound infections

Robotic surgery

Some surgeons may use a robotic machine to do part of the keyhole operation. The surgeon controls the machine using a specialised unit. The robotic machine gives the surgeon a better view of the inside of your abdomen. It also allows them to make finer movements.

Robotic surgery is still a newer technique, and not all NHS hospitals in the UK have this. Doctors hope that robotic surgery will cause less nerve damage and have fewer side effects. 

What happens after the operation

Your surgeon sends the cancer to the laboratory. A specialist doctor (pathologist) looks at it under a microscope. They check that the area of healthy tissue around the cancer is free of cancer cells. They call this a clear margin.

If there are cancer cells in the margin, your healthcare team will talk to you about further treatment.