The aim of this pilot study is to examine the collection of FoR levels in a longitudinal design with 100 breast cancer patients receiving radiotherapy for their disease. In this study, an intensive longitudinal design will be employed (Bolger & Laurenceau, 2013). There will be two data collection types. First, will be self-reported questionnaires. Patients will complete questions including three sections: 1) demographic information (i.e. age, education, employment, marital/family status), 2) a 7-item FoR scale (ACCRE FCR) and 3) a 20-item Affect Schedule (PANAS) before first radiation treatment (T1). Throughout the period of treatment, a 3-item FoR questionnaire (ACCRE FCR 3 Items) will be designed as a daily diary to monitor patient's FoR level. Then, at the end of the radiotherapy treatment (T2), PANAS will be measured again. Finally, six-eight weeks after the end of the treatment (T3), all participants will be asked to complete the 7-items FCR questionnaire once again as well as a 5-item EuroQoL EQ-5D-3L scale by telephone.