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Abdominal or pelvic radiotherapy side effects: pain

You might have pain after radiotherapy to the lower part of the abdomen (pelvis). This can happen some time after your radiothearpy has finished.

Why pain happens

It is important to see your doctor quickly if you have pain. Pain can occur for various reasons. The different causes are described below.


Bladder infections can cause pain and are more common after pelvic radiotherapy. The pain is usually worse when the bladder is full. It may be at its worst when you are passing urine or just afterwards. 

Your urine might be cloudy or smelly or have small amounts of blood. You might also feel ill, have a high temperature or feel sick (nauseated).

Your urine will need to be tested to find out which type of infection you have. Your doctor can then prescribe the correct antibiotic.

Bowel changes

Cramps (spasm) of the muscles lining the bowel can cause pain. This type of pain is made worse when you have your bowels open. The pain might come in waves. 

Constipation or a narrowing of the back passage (an anal stricture) can cause pain. Sometimes the pain can be due to a split in the skin of the anus known as a fissure. A fissure causes a very sharp and intense pain when you open your bowels. 

Your doctor might ask you to have an examination of the bowel to find out whether there are any changes. This examination is done by putting a flexible tube into the bowel (a flexible sigmoidoscopy).

A specialist in bowel problems (gastroenterologist) usually does this test.

Pelvic bone changes

Radiotherapy treatment for cancer in the pelvic area can sometimes lead to hip and pelvic bone problems later in life. Radiotherapy can damage bones in different ways. Problems after pelvic radiotherapy may include weaker bones and tiny cracks in the bones.

Weaker pelvic bones

Radiotherapy can damage the bone cells themselves, and also the supply of blood to the bones. The blood supply delivers nutrients (food) to the bones. Without these nutrients the bones become weaker. 

When bones are damaged because of a loss of blood supply, this is called avascular necrosis. Damage to the bones can cause pain and sometimes makes it hard to walk or climb stairs.

Your doctor might monitor you carefully after pelvic radiotherapy, including checking your bone strength with a DEXA scan. They may suggest treatment with painkillers and walking aids, such as a stick, to help you get around.

You might also take drugs to strengthen the bones called bisphosphonates. These drugs can help to control pain and reduce the risk of fractures.

Tiny cracks in the bones

Sometimes, tiny cracks can appear in the pelvic bones some years after radiotherapy. They are called pelvic insufficiency fractures. This is more likely to happen in people who have general weakening of their bones as they get older (osteoporosis). It is also more likely in people who are taking hormone therapies or steroids. 

The pain in this case can be quite bad. It usually gets worse if you move around or do exercise and gets better when you sit still or rest. This type of pain normally goes away overnight. It doesn't stop you from sleeping well.

Your doctor might ask you to have x-rays, a CT scan or an MRI scan (or a combination of these) to see if there are any fractures in the pelvic bones.

If there is a high risk of fracture your doctor might recommend a hip replacement or surgery to strengthen the bone. They will ask you to see an orthopaedic surgeon (a specialist in bone disease and repair).

Surgery for a hip replacement means a stay of about a week in hospital, as well as several weeks recovery time afterwards.

If the cancer comes back

Pain can also be caused if the cancer has come back. This is what many people who get pain after radiotherapy worry about most. You can talk to your doctor about the chance of your cancer coming back.

The pain might be there constantly, but for some people it comes and goes. It tends not to go away when you rest. Or it might get worse when you exercise or move around. The pain might also be there at night and keep you awake. The pain might not be very bad and could go away if you take mild painkillers. 

However, if you have this type of pain, your doctor should examine you. The doctor should arrange for you to have X-rays, a CT scan or an MRI scan or a combination of these to find the cause.

Last reviewed: 
22 Mar 2016
  • De Vita, Hellman, and Rosenberg's Cancer: Principles and Practice of Oncology (9th edition)
    De Vita, V.T., Lawrence, T.S. and Rosenberg S.A.
    Lippincott, Williams and Wilkins, 2011

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