Measuring female breast cancer survivors' concerns about late effects of treatment: initial development of the Concerns about Late Effects in Oncology Questionnaire (CLEO).

These findings suggest the CLEO captured concerns relevant to breast cancer survivors and provides initial validation of items for inclusion in the CLEO. The CLEO may improve communication about late effects in clinical settings and prompt future research into evidence-based interventions for survivors. Future research should assess the relevance of the CLEO items to other cancer populations. The psychometric properties of the CLEO will be evaluated in future stages of questionnaire development.