Breast cancer; Fatigue; RadiotherapyCáncer de mama; Fatiga; RadioterapiaCàncer de mama; Fatiga; RadioteràpiaFatigue is common in breast-cancer survivors. Our study assessed fatigue longitudinally in breast cancer patients receiving adjuvant radiotherapy (RT) and aimed to identify risk factors associated with long-term fatigue and underlying fatigue trajectories. Fatigue was measured in a prospective multicenter cohort (REQUITE) using the Multidimensional Fatigue Inventory (MFI-20) and analyzed using mixed models. Multivariable logistic models identified factors associated with fatigue dimensions at 2 years post-RT and latent class growth analysis identified individual fatigue trajectories. A total of 1443, 1302, 1203 and 1098 patients completed the MFI-20 at baseline, end of RT, after 1 and 2 years. Overall, levels of fatigue significantly increased from baseline to end of RT for all fatigue dimensions (P < .05) and returned to baseline levels after 2 years. A quarter of patients were assigned to latent trajectory high (23.7%) and moderate (24.8%) fatigue classes, while 46.3% and 5.2% to the low and decreasing fatigue classes, respectively. Factors associated with multiple fatigue dimensions at 2 years include age, BMI, global health status, insomnia, pain, dyspnea and depression. Fatigue present at baseline was consistently associated with all five MFI-20 fatigue dimensions (ORGeneralFatigue = 3.81, P < .001). From latent trajectory analysis, patients with a combination of factors such as pain, insomnia, depression, younger age and endocrine therapy had a particularly high risk of developing early and persistent high fatigue years after treatment. Our results confirmed the multidimensional nature of fatigue and will help clinicians identify breast cancer patients at higher risk of having persistent/late fatigue so that tailored interventions can be delivered.We thank all patients who participated in the REQUITE study and all the REQUITE staff involved in this project. Belgium: Ghent University Hospital; KU Leuven. France: ICM Montpellier, CHU Nîmes (Department of Radiation Oncology, CHU Nîmes, Nîmes, France). Germany: Zentrum für Strahlentherapie Freiburg (Dr. Petra Stegmaier); Städtisches Klinikum Karlsruhe (Dr. Bernhard Neu); ViDia Christliche Kliniken Karlsruhe (Prof. Johannes Claßen); Klinikum der Stadt Ludwigshafen GmbH (PD Dr. Thomas Schnabel); Universitätsklinikum Mannheim: Anette Kipke and Christiane Zimmermann; Strahlentherapie Speyer (Dr. Jörg Schäfer). The researchers at DKFZ also thank Anusha Müller, Irmgard Helmbold, Thomas Heger, Sabine Behrens, Axel Benner, Nicholas Schreck. Petra Seibold is supported by ERA PerMed 2018 funding (BMBF #01KU1912) and BfS funding (#3619S42261). Italy: Fondazione IRCCS Istituto Nazionale dei Tumori, Milano; Candiolo Cancer Institute – FPO, IRCCS. Tiziana Rancati was partially funded by Fondazione Italo Monzino. The Netherlands: Sylvie Canisius at Maastro Clinics, Maastricht. Spain: Barcelona: Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus; VHIO acknowledge the Cellex Foundation for providing research facilities and thank CERCA Programme/Generalitat de Catalunya for institutional support. Sara Gutiérrez-Enríquez is supported by ERAPerMed JTC2018 funding (ERAPERMED2018-244 and SLT011/18/00005). Santiago: Complexo Hospitalario Universitario de Santiago. Ana Vega: supported by Spanish Instituto de Salud Carlos III (ISCIII) funding, an initiative of the Spanish Ministry of Economy and Innovation partially supported by European Regional Development FEDER Funds (PI22/00589, PI19/01424; INT20/00071); the ERAPerMed JTC2018 funding (AC18/00117); the Autonomous Government of Galicia (Consolidation and structuring program: IN607B), by the Fundación Mutua Madrileña (call 2018) and by the AECC (PRYES211091VEGA); UK: University Hospitals of Leicester NHS Trust; Theresa Beaver, Kaitlin Walker and Sara Barrows. Dr Tim Rattay was funded by a National Institute of Health Research (NIHR) Clinical Lectureship (CL 2017-11-002) and is currently supported by the NIHR Leicester Biomedical Research Centre. He was previously funded by a National Institute of Health Research (NIHR) Doctoral Research Fellowship (DRF 2014-07-079). This publication presents independent research funded by the NIHR. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health. Manchester: Catharine West and Rebecca Elliott are supported by NIHR Manchester Biomedical Research Centre and Catharine West is supported by Cancer Research UK (C1094/A18504, C147/A25254). USA: Mount Sinai Hospital, New York. Open Access funding enabled and organized by Projekt DEAL
