title: A prospective study on the radiation therapy associated changes in body weight and bioelectrical standardized phase angle.
abstract: OBJECTIVE
  Standardized phase angle (SPA) is a value derived from bioelectrical impedance phase angle analysis and has been recognized as marker of nutritional risk and clinical status of cancer patients. This study aimed to evaluate the changes in SPA during radiation therapy of cancer patients and identify possible nutritional and clinical determinants of these changes.
  
  
  METHODS
  Nutritional assessment was performed before the initiation and at the end of the radiotherapy. It included anthropometrics and bioelectrical impedance analysis. A generalized linear mixed model was used to evaluate the effects of selected independent variables on the changes in standardized phase angle.
  
  
  RESULTS
  A total of 104 patients entered the study and those with complete information were included in the analysis (n = 62). Most patients (61%) were at clinical stage I and II, the most prevalent irradiation site was the pelvis (39%) and 98% were well nourished or overweight. According to the regression analysis, changes in body weight and irradiation at head and neck/upper abdomen and thorax were associated with standardized phase angle modifications during radiotherapy. Clinical stage and radiation dose were not associated with changes in standardized phase angle. Compared to baseline values, for every 1 kg weight reduction during the radiation therapy, the standardized phase angle also decreased by 0.107 (p < 0.0001).
  
  
  CONCLUSIONS
  In well nourished or overweight patients, weight loss during radiation therapy is closely associated with decrease in standard phase angle.
authors: Postgraduate Program in Human Nutrition, University of Brasília, Brasilia 70910-900, Distrito Federal, Brazil. Electronic address: e.paixao@yahoo.com.br.
authors: Elemárcia Martins da Silva
authors: EM
authors: Paixão
authors: Postgraduate Program in Health and Behavior, Catholic University of Pelotas, Pelotas, Rio Grande do Sul, Brazil.
authors: Maria Cristina
authors: MC
authors: Gonzalez
authors: Postgraduate Program in Human Nutrition, University of Brasília, Brasilia 70910-900, Distrito Federal, Brazil.
authors: Marina Kiyomi
authors: MK
authors: Ito
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D001835:Body Weight / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D017097:Electric Impedance; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000532:radiotherapy*; D015596:Nutrition Assessment; D009752:Nutritional Status; D050177:Overweight / Q000532:radiotherapy; D011446:Prospective Studies
keywords: Bioelectrical impedance; Body weight; Nutritional assessment; Radiotherapy; Standardized phase angle