A possible, but uncommon, late side effect of radiotherapy to the pelvic area is damage to the pelvic bones. Low sex hormone levels (caused by the effects of radiotherapy on the ovaries) may make the bones weaker and sometimes the bones in the treated area may also be directly weakened by the radiotherapy. Fine, hair-line cracks may occur, known as pelvic insufficiency fractures. If this happens, it can cause pain and may make it difficult to walk and move around. The weakening of the bones takes many months or years to happen. This can mean that you may be at more risk of fracturing a bone if you fall. The strength of your bones can be checked using a bone density scan.

The tiny cracks in the bone may cause a dull, constant ache and this may make you worry that the cancer has spread to the bone. However, tests can show that the ache or pain is caused by pelvic insufficiency fractures, rather than cancer in the bone. The cracks tend to be so small that they do not show up on an x-ray. So, if you have dull pain in the bone that goes on for a few weeks, your doctors will do tests (a bone scan, MRI scan or possibly a biopsy of the affected area) to find out the cause.

It is important to be aware of the signs of bone problems so you can let your doctor know if they occur. Radiotherapy damage to the bones is uncommon, so it is likely that if you have any symptoms they will have another cause. The section on pelvic pain discusses other causes of bone pain.

Dealing with bone damage

Treatment is given to relieve any symptoms that may be present. Drugs known as bisphosphonates can strengthen the bone and a diet rich in calcium can help pelvic insufficiency fractures to heal. If you are able to take HRT, that may also help to strengthen the bone. If you are in pain, this can usually be controlled with painkillers. You may also need to see a physiotherapist or occupational therapist if the damaged bone makes it difficult for you to move around and carry out daily activities.