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Internal radiotherapy for rectal cancer

Internal radiotherapy means giving radiotherapy to the cancer from inside of the back passage (rectum). It is also called brachytherapy.

You usually have internal radiotherapy as an outpatient. 

The treatment gives a high dose of radiation to the cancer but very little to surrounding tissues. It can shrink the cancer, relieve symptoms and help you feel more comfortable. It might slow the growth of the cancer and it can reduce pain.

This page is about internal radiotherapy for cancer of the back passage (rectal cancer). You don’t usually have internal radiotherapy for large bowel (colon) cancer.

Types of internal radiotherapy

There are 2 types of internal radiotherapy for rectal cancer:

  • High dose rate brachytherapy (HDR)
  • Contact x-ray bracytherapy (Papillon)

High dose rate (HDR)

Your bowels need to be empty for the treatment. To do this you have an enema before treatment. An enema is a small liquid filled pouch with a nozzle, that you put into your back passage.

Your treatment team helps you to get into the right position on the couch. You might have the procedure under sedation. 

The treatment can take about 10 to 15 minutes. The doctor numbs the area with a local anaesthetic gel. They then gently push a tube through the anus and into your rectum. Then, they attach the tube to the internal radiotherapy machine.

The treatment team leaves you in the room. And watch you from a TV monitor. You can talk to them through an intercom. 

The radioactive source moves from the machine into the tube by remote control. Once in place it delivers radiation to the tumour. The radioactive source moves back into the machine. And your doctor takes the tube out.    

You can then go home. If you have had a sedative you'll need a friend or relative with you. If you're having this treatment before surgery, you usually have your operation a few weeks later.

Contact x-ray brachytherapy (Papillon)

Contact x-ray brachytherapy (CXB) uses low dose x-rays to treat the cancer. It is also called contact radiotherapy (Papillon). The radiotherapy only goes a few millimetres into the tissue. So there is less damage to normal surrounding tissues which reduces the side effects.

You might have contact x-ray brachytherapy:

  • if you have an early cancer
  • if your cancer measures less than 3cm
  • if you can't, or don't want to have surgery

This treatment is only available in a few hospitals. So you might need to travel to have it. 

Before treatment you have a low fibre diet for 3 days. Just before you have treatment, you have a small amount of liquid (an enema) put into the rectum. This is to help clear it out.

Your doctor puts some local anaesthetic gel around the anus to numb the area. And some cream to relax the muscles.  

The treatment takes just over 2 minutes. But you will probably be in the radiotherapy department for about 30 minutes. Your doctor examines your rectum using a small tube called a sigmoidoscope. Then, they gently put an applicator into the rectum. The doctor puts the treatment tube through the applicator. This is attached to a machine that gives radiation to the tumour. 

You have more treatment 2 weeks later. And if your cancer gets better, you may continue having treatment every 2 weeks. You have up to 3 treatments in total. The number of treatments you have depends on your cancer and whether you first had surgery to remove the cancer. If this is the case you might then have 2 treatments. 

You may need surgery if this treatment does not work as well as expected. Or you might have surgery if your cancer starts to grow again at a later date. 

Side effects

Possible side effects of high dose rate brachytherapy to the rectum include:

  • bleeding from the back passage
  • pain and discomfort
  • a hole (fistula) between the rectum and the bladder or vagina but this is rare
  • narrowing (stenosis) of the rectum

These side effects are rare. You have regular check ups with your medical team who will ask about symptoms and how you are.

The most common side effects of contact x-ray brachytherapy include:

  • bleeding from the back passage – this usually settles down within 3 to 6 months
  • pain and discomfort in some people due to inflammation of the rectum – you are shown how to use steroid enemas when at home to reduce this and it usually settles down within 2 to 6 weeks after treatment finishes
  • an ulcer in the rectum where the tumour was – this usually isn’t painful and heals after 3 to 6 months but sometimes it takes longer

Another possible side effect is narrowing (stenosis) of the rectum. But this is rare.

You have regular check ups with your medical team who will ask about symptoms and how you are.