People with breast cancer should not avoid exercise because of groundless fears it will cause or worsen a type of incurable and painful swelling. That's according to the National Institute for Health and Care Excellence (NICE), which has updated its guidance on the care of people with advanced breast cancer to clarify the link between exercise and breast cancer-related lymphoedema.

Of the nearly 50,500 Britons who are diagnosed with breast cancer each year, 1 in 5 - about 10,000 people - will develop lymphoedema in the arm following treatment. This is a painful condition which makes joints stiff and difficult to move.

Lymphoedema occurs when the body's lymphatic system - part of the immune system - becomes damaged and is unable to drain fluid normally. This leads to a build-up of fluid in the arms and surrounding areas, causing painful swelling.

It can be caused by surgery or radiotherapy, or if the lymphatic system becomes blocked by cancer cells. There is currently no cure.

Professor Mark Baker, Director of the NICE Centre for Clinical Practice, said: "Lymphoedema can have a significant effect on someone's life, making once routine tasks difficult and painful. It may also have an impact on a person's self-confidence and mental health depending on how severe the condition is.

"Our new recommendations make clear the link between exercise and breast cancer-related lymphoedema to help people manage this often distressing condition. Although exercise will not prevent it, evidence shows that it will not cause lymphoedema or make existing symptoms worse either."

The updated NICE guidance is aimed at doctors and nurses caring for people with breast cancer. It says that patients with or at risk of breast cancer-related lymphoedema should be told that:

  • exercise will not prevent, cause or worsen lymphoedema for people with or at risk of the condition.
  • exercise may improve their quality of life.

Rachel Rawson, Clinical Nurse Specialist at Breast Cancer Care, said: "Lymphoedema after breast cancer treatment can be devastating. It attacks confidence and self-esteem and can reduce a person's quality of life.

"It's so important that NICE is highlighting this new evidence about the safety of exercise and lymphoedema. Knowing that exercise can be beneficial will give confidence to those living with the condition.

"Exercise can also help maintain or improve health for anyone diagnosed with breast cancer. Regular movement every day can help keep joints supple and aid lymph drainage and extra exercises can also be useful if swelling restricts movement of the arm."

The new recommendations on the link between exercise and breast cancer-related lymphoedema have updated the NICE guidance on advanced breast cancer. All other recommendations are unchanged. These recommendations are also relevant for people with early stage breast cancer.