Dropout from exercise trials among cancer survivors: An individual patient data meta-analysis from the POLARIS study

Benedikte Western*, Andreas Ivarsson, Ingvild Vistad, Ingrid Demmelmaier, Neil K Aaronson, Gillian Radcliffe, Marc van Beurden, Martin Bohus, Kerry S Courneya, Amanda J Daley, Daniel A Galvão, Rachel Garrod, Martine M Goedendorp, Kathleen A Griffith, Wim H van Harten, Sandi C Hayes, Fernando Herrero-Roman, Anouk E Hiensch, Melinda L Irwin, Erica JamesMarlou-Floor Kenkhuis, Marie José Kersten, Hans Knoop, Alejandro Lucia, Anne M May, Alex McConnachie, Willem van Mechelen, Nanette Mutrie, Robert U Newton, Frans Nollet, Hester S Oldenburg, Ron Plotnikoff, Martina E Schmidt, Katie H Schmitz, Karl-Heinz Schulz, Camille E Short, Gabe S Sonke, Karen Steindorf, Martijn M Stuiver, Dennis R Taaffe, Lene Thorsen, Miranda J Velthuis, Jennifer Wenzel, Kerri M Winters-Stone, Joachim Wiskemann, Sveinung Berntsen, Laurien M Buffart*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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INTRODUCTION: The number of randomized controlled trials (RCTs) investigating the effects of exercise among cancer survivors has increased in recent years; however, participants dropping out of the trials are rarely described. The objective of the present study was to assess which combinations of participant and exercise program characteristics were associated with dropout from the exercise arms of RCTs among cancer survivors.

METHODS: This study used data collected in the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) study, an international database of RCTs investigating the effects of exercise among cancer survivors. Thirty-four exercise trials, with a total of 2467 patients without metastatic disease randomized to an exercise arm were included. Harmonized studies included a pre and a posttest, and participants were classified as dropouts when missing all assessments at the post-intervention test. Subgroups were identified with a conditional inference tree.

RESULTS: Overall, 9.6% of the participants dropped out. Five subgroups were identified in the conditional inference tree based on four significant associations with dropout. Most dropout was observed for participants with BMI >28.4 kg/m 2 , performing supervised resistance or unsupervised mixed exercise (19.8% dropout) or had low-medium education and performed aerobic or supervised mixed exercise (13.5%). The lowest dropout was found for participants with BMI >28.4 kg/m 2 and high education performing aerobic or supervised mixed exercise (5.1%), and participants with BMI ≤28.4 kg/m 2 exercising during (5.2%) or post (9.5%) treatment.

CONCLUSIONS: There are several systematic differences between cancer survivors completing and dropping out from exercise trials, possibly affecting the external validity of exercise effects.

Original languageEnglish
Article numbere14575
Number of pages10
JournalScandinavian Journal of Medicine & Science in Sports
Issue number2
Publication statusPublished - Feb-2024


  • Humans
  • Cancer Survivors
  • Quality of Life
  • Exercise
  • Exercise Therapy
  • Neoplasms/rehabilitation
  • Randomized Controlled Trials as Topic


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