title: Relationship between fatigue, sleep quality and inflammatory cytokines during external beam radiation therapy for prostate cancer: A prospective study.
abstract: OBJECTIVE
  Mechanisms of fatigue reported during radiotherapy are poorly defined but may include inflammatory cytokines and/or sleep disturbances. This prospective, longitudinal, phase II study assessed fatigue, sleep, and serum cytokine levels during radiotherapy for early-stage prostate cancer (PCa).
  
  
  METHODS
  Twenty-eight men undergoing radiotherapy for early-stage PCa wore an Actiwatch Score to record fatigue level, sleep time, onset latency, efficiency and wake after sleep onset. Serum levels of IL-1α, IL-1β, TNF-α, IL-6, IL-8, IL-10 and VEGF were measured weekly during radiotherapy. Patient reported quality of life (QOL) metrics were collected before and after treatment. Linear mixed effects models examined trajectories across treatment weeks.
  
  
  RESULTS
  Fatigue increased across treatment weeks (P<.01), and fatigue was associated with decreased patient-reported QOL. Sleep efficiency increased across treatment weeks (rate of change over time=.29, P=.03), and sleep onset latency decreased (rate of change over time=.86, P=.06). IL-6 tended to increase during treatment (P=0.09), but none of the cytokine levels or sleep variables were significantly related to fatigue trajectories.
  
  
  CONCLUSIONS
  Despite increased sleep efficiency across treatment weeks, fatigue significantly increased. Although IL-6 increased during the course of radiotherapy, cytokines levels were not associated with fatigue scores or sleep disturbance. Further studies are needed to define the mechanisms for fatigue during radiotherapy.
authors.affiliation: The University of Texas MD Anderson Cancer Center Division of Radiation Oncology, Houston, United States.
authors.forename: Emma B
authors.initials: EB
authors.lastname: Holliday
authors.affiliation: Oregon Health & Science University School of Nursing, Department of Public Health and Preventative Medicine & Department of Psychiatry, Portland, United States.
authors.forename: Nathan F
authors.initials: NF
authors.lastname: Dieckmann
authors.affiliation: Oregon Health & Science University Department of Radiation Medicine, Portland, United States.
authors.forename: Tasha L
authors.initials: TL
authors.lastname: McDonald
authors.affiliation: Oregon Health & Science University Department of Radiation Medicine, Portland, United States.
authors.forename: Arthur Y
authors.initials: AY
authors.lastname: Hung
authors.affiliation: Oregon Health & Science University Department of Radiation Medicine, Portland, United States.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Thomas
authors.affiliation: The University of Texas MD Anderson Cancer Center Division of Radiation Oncology, Houston, United States; Massachussettes General Hospital Institute of Health Professions, Boston, United States. Electronic address: ljwood@mghihp.edu.
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Wood
mesh_terms: D000368:Aged; D016207:Cytokines / Q000097:blood*; D005221:Fatigue / Q000097:blood / Q000209:etiology*; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011788:Quality of Life; D011832:Radiation Injuries / Q000097:blood / Q000209:etiology; D012893:Sleep Wake Disorders / Q000097:blood / Q000209:etiology*; D012959:Socioeconomic Factors; D014555:Urination Disorders / Q000097:blood / Q000209:etiology
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators
keywords: Cancer treatment related fatigue; Cytokines; Prosate Cancer; Radiotherapy; Sleep disturbance