title: Efficacy of preoperative combined 18-fluorodeoxyglucose positron emission tomography and computed tomography for assessing primary rectal cancer response to neoadjuvant therapy.
abstract: OBJECTIVE
  Efficacy of F-18 fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) for determining neoadjuvant therapy response in rectal cancer is not well established. We sought to evaluate serial FDG-PET/CT for assessing tumor down-staging, percentage residual tumor, and complete response or microscopic disease with rectal cancer neoadjuvant therapy.
  
  
  METHODS
  Patients with rectal cancer undergoing neoadjuvant therapy, definitive surgical resection, and FDG-PET/CT before and 4-6 weeks after neoadjuvant treatment were included. Tumors were evaluated pretreatment and on final pathology for size and stage. FDG-PET/CT parameters assessed were visual response score (VRS), standardized uptake value (SUV), PET-derived tumor volume (PETvol), CT-derived tumor volume (CTvol), and total lesion glycolysis (delta TLG).
  
  
  RESULTS
  Twenty-one rectal cancer patients over 3 years underwent neoadjuvant treatment, serial FDG-PET/CT, and resection. Complete response or microscopic disease (n = 7, 33%) was associated with higher Delta CTvol (AUC = 0.82, p = 0.004) and Delta SUV (AUC = 0.79, p = 0.01). Tumor down-staging (n = 14, 67%) was associated with greater Delta PETvol (AUC = 0.82, p < 0.001) and Delta SUV (AUC = 0.82, p < 0.001). Pathologic lymph node disease (n = 7, 33%) correlated with Delta CTvol (AUC = 0.75, p = 0.03) and Delta PETvol (AUC = 0.70, p = 0.08).
  
  
  CONCLUSIONS
  FDG-PET/CT parameters were best for assessing tumor down-staging and percentage of residual tumor after neoadjuvant treatment of rectal cancer and can potentially assist in treatment planning.
authors.affiliation: Department of Surgery, The Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD 21287, USA.
authors.forename: Genevieve B
authors.initials: GB
authors.lastname: Melton
authors.forename: William C
authors.initials: WC
authors.lastname: Lavely
authors.forename: Heather A
authors.initials: HA
authors.lastname: Jacene
authors.forename: Richard D
authors.initials: RD
authors.lastname: Schulick
authors.forename: Michael A
authors.initials: MA
authors.lastname: Choti
authors.forename: Richard L
authors.initials: RL
authors.lastname: Wahl
authors.forename: Susan L
authors.initials: SL
authors.lastname: Gearhart
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000601:surgery* / Q000628:therapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D049268:Positron-Emission Tomography; D011300:Preoperative Care; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000601:surgery* / Q000628:therapy; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18