title: Changes in symptom clusters in patients undergoing radiation therapy.
abstract: OBJECTIVE
  The goals of the study were to determine the occurrence rates for and the severity of symptoms at the middle, end, and 1 month after the completion of radiation therapy (RT), to determine the number and types of symptom clusters at these three time points, and to evaluate for changes over time in these symptom clusters.
  
  
  METHODS
  Symptom occurrence and severity were evaluated using the Memorial Symptom Assessment Scale (MSAS) in a sample of patients (n = 160) who underwent RT for breast or prostate cancer. At each time point, an exploratory factor analysis was done to determine the number of symptom clusters (i.e., symptom factors) based on the MSAS symptom severity ratings.
  
  
  RESULTS
  The majority of the patients were male and married with a mean age of 61.1 years. The five symptoms with the highest occurrence rates across all three time points were lack of energy, pain, difficulty sleeping, feeling drowsy, and sweats. Although the number of symptoms and the specific symptoms within each symptom cluster were not identical across the three time points, three relatively similar symptom clusters (i.e., "mood-cognitive" symptom cluster, "sickness-behavior" symptom cluster, "treatment-related", or "pain" symptom cluster) were identified in this sample. The internal consistency coefficients for the mood-cognitive symptom cluster and sickness-behavior symptom cluster were adequate at > or =0.68.
  
  
  CONCLUSIONS
  Three relatively stable symptom clusters were found across RT. The majority of the symptom cluster severity scores were significantly higher in patients with breast cancer compared to patients with prostate cancer.
authors.affiliation: School of Nursing, University of California, San Francisco, CA, USA.
authors.forename: Esther
authors.initials: E
authors.lastname: Kim
authors.forename: Thierry
authors.initials: T
authors.lastname: Jahan
authors.forename: Bradley E
authors.initials: BE
authors.lastname: Aouizerat
authors.forename: Marylin J
authors.initials: MJ
authors.lastname: Dodd
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Cooper
authors.forename: Steven M
authors.initials: SM
authors.lastname: Paul
authors.forename: Claudia
authors.initials: C
authors.lastname: West
authors.forename: Kathryn
authors.initials: K
authors.lastname: Lee
authors.forename: Patrick S
authors.initials: PS
authors.lastname: Swift
authors.forename: William
authors.initials: W
authors.lastname: Wara
authors.forename: Christine
authors.initials: C
authors.lastname: Miaskowski
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D016000:Cluster Analysis; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D055809:Illness Behavior / Q000528:radiation effects*; D017567:Karnofsky Performance Status; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D011788:Quality of Life / Q000523:psychology*; D011832:Radiation Injuries; D012959:Socioeconomic Factors