DISCUSSION
cancer, PA behavior
CANCER
This analysis (To estimate the true treatment effect of an RCT, it is important that the intervention and the control group adhere to their allocated study program. The definition of adherence differs across exercise studiesPA hours of the intervention group were self‐reported in a web‐based diary, which has been successfully used for assessing adherence in RCTs also in cancer survivors.We found descending intervention week, female sex, and low physical and mental quality of life to be significant positive predictors for intervention adherence. This is in agreement with most studies that reported a high adherence in short‐term, but a striking loss of adherence in long‐term PA trials.For the control group, no significant predictors for study contamination were found which may be partly explained by the small sample size in the “contaminated” group. Misclassification based on reporting bias cannot be ruled out either. As trials are always prone to a clear selection bias toward those willing and ready to increase their PA behavior, other designs such as SCEDs as mentioned above could be a solution to solve this problem.Predictors of adherence to the intervention can help to understand adherence in trials focusing on behavioral change, for example, whom we might reach and why. Female compared to male sex is globally associated with poorer PA during adolescence in the healthy population and CCS.