The evidence behind our guidance

Every health page on Breast Cancer Fitness is referenced. This section explains the main research behind our guidance in plain English, including where the evidence is strong and where it’s still developing.

What the evidence covers

How strong is the evidence?

Strength of evidence, from strongest to weakest: guidelines and systematic reviews, randomised controlled trials, observational studies, and expert opinion.
  • Systematic reviews and guidelines bring together many studies, and give the most reliable picture.
  • Randomised controlled trials compare groups who are randomly given a treatment or not, and are the best way to test whether something works.
  • Observational studies follow groups of people over time. They can show links, but can’t prove cause and effect.
  • Expert opinion is useful where research is limited, but is the least certain.

We say how strong the evidence is, and when a claim comes from a company or a single study. Read our editorial policy.

The headline findings

  • Being active during and after treatment improves fatigue, anxiety, depression, physical function and quality of life, and doesn’t make lymphoedema worse.1
  • Prehab before breast cancer surgery is safe and practical, and studies are promising, although trials are still small.2
  • Body weight after diagnosis has the strongest link with survival among diet and lifestyle factors. Evidence for individual foods is limited.3

Everyone’s treatment is different, so talk to your cancer team about what is right for you.

References

  1. Campbell KL, Winters-Stone KM, Wiskemann J, et al. Exercise guidelines for cancer survivors: consensus statement from international multidisciplinary roundtable. Medicine & Science in Sports & Exercise. 2019;51(11):2375–2390. doi.org/10.1249/MSS.0000000000002116
  2. Toohey K, Hunter M, McKinnon K, Casey T, Turner MR, Taylor S, Paterson C. A systematic review of multimodal prehabilitation in breast cancer. Breast Cancer Research and Treatment. 2023;197(1):1–37. doi.org/10.1007/s10549-022-06759-1
  3. World Cancer Research Fund. Breast cancer survivors: Global Cancer Update Programme (CUP Global) findings on body weight, physical activity and diet after diagnosis. www.wcrf.org/research-policy/evidence-for-our-recommendations/after-a-cancer-diagnosis-follow-recommendations/breast-cancer-survivors-research/