Contentslistsavailableat ScienceDirect EuropeanJournalofOncologyNursing journal homepage: www.elsevier.com/locate/ejon Symptomclustersinpatientswithbreastcancerreceivingradiationtherapy Selina Chow a ,BoAngelaWan a ,WilliamPidduck a ,LiyingZhang a ,CarloDeAngelis a , Stephanie Chan a ,CaitlinYee a ,LeahDrost a ,EricLeung a ,PhilomenaSousa a ,DonnaLewis a , HenryLam a ,RonaldChow b ,MichaelLock b ,EdwardChow a,* a Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada b London Regional Cancer Program, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada ARTICLEINFO Keywords: Breast cancer Edmonton symptom assessment system Symptom clusters Radiotherapy ABSTRACT Purpose: Symptomsexperiencedbybreastcancerpatientsoftenclustertogetheringroupsknownas“symptom clusters”.Theaimwastodeterminethesymptomclustersinwomenwithnon-metastaticbreastcancertreated byradiationtherapy(RT). Methods: EdmontonSymptomAssessmentScale(ESAS)scoresweretakenfrombreastcancerpatientsreceiving RTbefore,atcompletionofRT,andafterRT.Exploratoryfactoranalysis(EFA),principalcomponentanalysis (PCA), and hierarchical cluster analysis (HCA) were used to identify symptom clusters among the nine ESAS itemsatallthreetimepoints. Results: Thisstudyincluded1224patients.ThePCAandEFAidentifiedthesametwosymptomclustersbefore the start of RT: 1) pain, tiredness, nausea, drowsiness, appetite, and dyspnea; 2) depression, anxiety, and wellbeing. The HCA further split the symptoms into three clusters. Wellbeing, depression, and anxiety con- sistentlyclusteredtogether.AmongtheESASscorescollectedattheendofandafterRT,eachstatisticalmethod identified different symptom clusters. For the symptom clusters experienced at the end of RT, the following symptomswerealwaysinthesamecluster:wellbeing,depression,andanxiety;nauseaandappetite;drowsiness anddyspnea.FollowingRT,depressionandanxietyconsistentlyclusteredtogether,withnauseaandappetitein asecondcluster. Conclusion: Amongthesymptomclustersderivedbefore,attheendofRT,andafterRT,thefollowingsymptoms consistently presented together: depression and anxiety, nausea and appetite, pain and tiredness, and drowsi- ness, dyspnea, and tiredness. Understanding symptom clusters in this population can improve management of symptoms. 1. Introduction Breast cancer patients typically receive systemic treatments, radia- tion therapy (RT), and/or surgery (Nguyen et al., 2011). While the disease in itself does not typically lead to specific symptoms in the absenceofmetastases,symptomsmaybearesulttreatment-relatedor psychosocial aspects of the illness (Kim et al., 2008; Matthews et al., 2012).Withincreasedsurvivalratesforindividualswithbreastcancer, improving the quality of life and symptom management of survivors havebecomeincreasinglyimportantprioritiesinclinicalcare(Nguyen etal.,2011). Breast cancer patients usually experience fatigue, depression, me- nopausalsymptomsandothers(Doddetal.,2010; Nguyenetal.,2011). Mostofthetime,symptomsdonotoccurinisolation,butrather,several symptomsoccursimultaneously.Duetothisconcurrenceofsymptoms, earlier studies aimed at treating individual symptoms did not always improvequalityoflife(Miaskowski,2006).Systematicattentiontothe presenceofsymptomsincancerpatientsledtotheconceptofsymptom clusters(Chowetal.,n.d.).In2001,Doddetal.wereoneofthefirstto definea“symptomcluster”consistingofthreeormoreconcurrentand related symptoms, which do not necessarily share the same etiology (Dodd et al., 2001). According to Kim et al., a symptom cluster is a stable group of two or more related symptoms that occur together, which is relatively independent of other clusters (Kim et al., 2005; KirkovaandWalsh,2007). There are relatively few breast symptom cluster studies conducted todate;someexistingstudieshaveevaluatedhowthesymptomclusters experiencedbypatientswithbreastcancerchangeacrossdifferenttime https://doi.org/10.1016/j.ejon.2019.07.004 Received16April2019;Receivedinrevisedform2July2019;Accepted8July2019 * Correspondingauthor.DepartmentofRadiationOncologyOdetteCancerCentre,SunnybrookHealthSciencesCentre,2075BayviewAvenueToronto,Ontario, M4N3M5,Canada. E-mail address: edward.chow@sunnybrook.ca (E.Chow). European Journal of Oncology Nursing 42 (2019) 14–20 1462-3889/ © 2019 Elsevier Ltd. All rights reserved. T