Background: The ongoing multi-center randomized FURCA-trial investigates the effect of patient-led follow-up after rectal cancer, aiming at improving management of late effects and survivorship care. The purpose of this present sub-study was to identify potential systematic differences between participants and non-participants in the FURCA-trial, in regard to demographic and clinical factors at baseline, and in quality of life (QoL) and fear of cancer recurrence (FCR) after one year. Material and methods: The population comprised patients invited to the FURCA-trial during the first 13 months' recruitment. Clinical and demographic data was obtained at baseline and differences were significance tested. Non-participants were requested to fill in a short survey one year after primary surgery, while participants received the questionnaires as part of more comprehensive one-year follow-up. Results: In the first 13 months of the trial, 113 out of the 262 patients invited, declined to participate. The main reason reported for this was lack of energy surplus. Participants were younger than non-participants (p < .01), and nonparticipation was particularly evident among patients ≥ 80 years. More than half of the invited females declined to participate. Good WHO Performance status was associated with participation (p = .01), yet there were no statistically significant differences in Charlson Comorbidity Index, type of surgery, oncological treatment or UICC stages between participants and non-participants. By one year after surgery, there was no difference in FCR-level (p = .92) and QoL (p = .25) between the non-participants and control group participants. Conclusion: The sub-study found that participants and non-participants differed at baseline in regard to age, gender and performance status, which is supported by results from other studies. No between-group differences were found in psychological factors after one year. These findings are important for the generalisability of the upcoming results from the trial.