title: Liver metabolic activity changes over time with neoadjuvant therapy in locally advanced rectal cancer.
abstract: OBJECTIVE
  The aim of this study was to evaluate, using PET/computed tomography (CT), changes in liver metabolic activity in patients with locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (CRT).
  
  
  METHODS
  A total of 29 biopsy-proven LARC patients between 2009 and 2012 were studied. Liver standardized uptake values (SUVs) and SUVs adjusted for lean body mass (SULs) were obtained from PET/CT images obtained at 1 h (early) and 2 h (late) after (18)F-fluorodeoxyglucose ((18)F-FDG) administration both before and after neoadjuvant CRT. Age, sex, BMI, lean body mass, blood glucose level, and (18)F-FDG dose, which can influence liver SUVs and SULs, were also analyzed.
  
  
  RESULTS
  Fourteen (48%) men and 15 (52%) women with a mean age of 62±11 years (range 34-80 years) were included in the study. The mean SUVs and SULs were significantly decreased in the late scans. Sex was significantly correlated with the mean liver SUV in early and late scans. The mean SUV differed significantly between male and female patients in early and late images (P<0.05). In a multivariate stepwise regression analysis, only liver SUVs (maximum and mean) were significantly associated with BMI before and after therapy. SUVs were significantly higher in the high (≥25) BMI group after but not before therapy. Mean SUL was not influenced by BMI.
  
  
  CONCLUSIONS
  Liver (18)F-FDG uptake is consistent before and after neoadjuvant CRT therapy in patients with LARC. When assessing response to therapy and using liver metabolic activity to indicate background activity, BMI should be considered as it can influence liver metabolic activity.
authors.affiliation: aDepartment of Nuclear Medicine, School of Medicine, Yüzüncü Yil University, Van bDepartment of Nuclear Medicine, School of Medicine, Pamukkale University, Denizli cDepartment of Nuclear Medicine, Atatürk Government Hospital, Aydin dDepartment of Nuclear Medicine, School of Medicine, Dokuz Eylül University, İzmir, Turkey.
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Demir
authors.forename: Erdem
authors.initials: E
authors.lastname: Sürücü
authors.forename: Tarik
authors.initials: T
authors.lastname: Şengöz
authors.forename: Murat
authors.initials: M
authors.lastname: Koç
authors.forename: Gamze Ç
authors.initials: GÇ
authors.lastname: Kaya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D012004:Rectal Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology* / Q000628:therapy*; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18