title: Fatigue during breast radiotherapy and its relationship to biological factors.
abstract: BACKGROUND
  Fatigue is commonly reported in patients receiving radiotherapy for breast conservation, but the underlying mechanisms remain unclear.
  
  
  METHODS
  Patients with early breast cancer participating in a prospective study of the impact of inflammatory processes on early and delayed breast morbidity were assessed for fatigue levels using the Functional Assessment of Cancer Therapy (FACT) fatigue subscale before and at intervals during and after radiotherapy. Blood for analysis of a variety of circulating cytokines, coagulation factors, peripheral blood indices and biochemical factors was collected at the same time points.
  
  
  RESULTS
  Fifty-two eligible patients were assessed. Twenty-one patients (43%) developed significant fatigue during radiotherapy, whereas 28 (54%) developed minimal or no fatigue. Fatigue appeared to plateau between week 4 of treatment and 2 weeks after treatment. The fatigue was beginning to settle by 6 weeks after treatment. Significant fatigue was predicted by a higher baseline fatigue score, red cell count, neutrophil count, and D-dimer level. Baseline fatigue correlated with higher body mass index, C-reactive protein, soluble thrombomodulin, tissue plasminogen activator, von Willebrand factor antigen, interleukin-6, ICAM-1, hemoglobin and red cell, monocyte, and neutrophil counts. There were also significant correlations between body mass index and tissue plasminogen activator, C-reactive protein, interleukin-6, ICAM-1, and red cell count. After these factors were controlled for, baseline fatigue was seen to be associated with higher body mass index, soluble thrombomodulin, tissue plasminogen activator, von Willebrand factor antigen, monocyte count, and neutrophil count. Multiple logistic regression procedures indicated that the most predictive factors for fatigue during radiotherapy were higher baseline fatigue level and higher baseline neutrophil and red cell counts.
  
  
  CONCLUSIONS
  This study has shown that significant fatigue is common in patients receiving breast irradiation and is precipitated during radiotherapy in some patients but not others. The factors shown to be associated with fatigue in this study will be helpful in shaping future studies.
authors.affiliation: Department ofRadiation Oncology, Newcastle Mater Misericordiae Hospital, Waratah, NSW, Australia. Chris.Wratten@mater.health.nsw.gov.au
authors.forename: Christopher
authors.initials: C
authors.lastname: Wratten
authors.forename: Janice
authors.initials: J
authors.lastname: Kilmurray
authors.forename: Sharon
authors.initials: S
authors.lastname: Nash
authors.forename: Michael
authors.initials: M
authors.lastname: Seldon
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hamilton
authors.forename: Peter C
authors.initials: PC
authors.lastname: O'Brien
authors.forename: J W
authors.initials: JW
authors.lastname: Denham
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000097:blood / Q000532:radiotherapy*; D002097:C-Reactive Protein / Q000032:analysis; D005221:Fatigue / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008875:Middle Aged; D011446:Prospective Studies; D011878:Radiotherapy / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D012720:Severity of Illness Index; D010959:Tissue Plasminogen Activator / Q000097:blood
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D018799:Intercellular Adhesion Molecule-1; D002097:C-Reactive Protein; D010959:Tissue Plasminogen Activator