title: Predicting pathological response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer using 18FDG-PET/CT.
abstract: BACKGROUND
  Pathologic complete response (pCR) after neoadjuvant chemoradiation (CRT) has been observed in 15-30% of patients with locally advanced rectal cancer (LARC). The objective of this study was to determine whether PET/CT can predict pCR and disease-free survival in patients receiving CRT with LARC.
  
  
  METHODS
  This is a retrospective review of patients with EUS-staged T3-T4, N+rectal tumors treated with CRT, who underwent pre/post-treatment PET/CT from 2002-2009. All patients were treated with CRT and surgical resection. Standardized uptake value (SUV) of each tumor was recorded. Logistic regression was used to analyze the association of pre-CRT SUV, post-CRT SUV, %SUV change, and time between CRT and surgery, compared with pCR. Kaplan-Meier estimation evaluated significant predictors of survival.
  
  
  RESULTS
  Seventy patients (age 62 years; 42M:28F) with preoperative stage T3 (n=61) and T4 (n=9) underwent pre- and post-CRT PET/CT followed by surgery. The pCR rate was 26%. Median pre-CRT SUV was 10.8, whereas the median post-CRT SUV was 4 (P=0.001). Patients with pCR had a lower median post-CRT SUV compared with those without (2.7 vs. 4.5, P=0.01). Median SUV decrease was 63% (7.5-95.5%) and predicted pCR (P=0.002). Patients with a pCR had a greater time interval between CRT and surgery (median, 58 vs. 50 days) than those without (P=0.02). Patients with post-CRT SUV<4 had a lower recurrence compared with those without (P=0.03). Patients with SUV decrease≥63% had improved overall survival at median follow-up of 40 months than those without (P=0.006).
  
  
  CONCLUSIONS
  PET/CT can predict response to CRT in patients with LARC. Posttreatment SUV, %SUV decrease, and greater time from CRT to surgery correlate with pCR. Post-CRT, SUV<4, and SUV decrease≥63% were predictive of recurrence-free and overall survival.
authors.affiliation: Department of Surgery, Temple University, Philadelphia, PA, USA. sshanmug@temple.edu
authors.forename: Skandan
authors.initials: S
authors.lastname: Shanmugan
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Arrangoiz
authors.forename: James R
authors.initials: JR
authors.lastname: Nitzkorski
authors.forename: Jian Q
authors.initials: JQ
authors.lastname: Yu
authors.forename: Tianyu
authors.initials: T
authors.lastname: Li
authors.forename: Harry
authors.initials: H
authors.lastname: Cooper
authors.forename: Andre
authors.initials: A
authors.lastname: Konski
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Farma
authors.forename: Elin R
authors.initials: ER
authors.lastname: Sigurdson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D000069287:Capecitabine; D059248:Chemoradiotherapy; D017024:Chemotherapy, Adjuvant; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D019788:Fluorodeoxyglucose F18; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology / Q000628:therapy; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy*; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D003841:Deoxycytidine; D019788:Fluorodeoxyglucose F18; D000069287:Capecitabine; D005472:Fluorouracil