title: Predictive value of (18)FDG PET-CT for tumour response in patients with locally advanced rectal cancer treated by preoperative chemoradiotherapy.
abstract: OBJECTIVE
  Although (18)fluorine-2-deoxy-D-glucose positron emission tomography-computed tomography ((18)FDG PET-CT) is considered a reliable modality for determining tumour response after neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC), the role of (18)FDG PET-CT for predicting pathologic complete response (pCR) remains unclear. The aim of this study was to evaluate whether (18)FDG PET-CT can predict tumour response after CRT in patients with LARC, in terms of downstaging and pCR.
  
  
  METHODS
  Between March 2009 and February 2012, 151 patients with LARC treated with neoadjuvant CRT followed by radical surgery were reviewed retrospectively. Pre-CRT SUVmax (maximum standardized uptake value), post-CRT SUVmax, ΔSUVmax (difference between pre- and post-CRT SUVmax), and RI-SUV (response index) were measured before and after CRT. Univariate and multivariate analyses were used to analyse the association of PET-CT-related parameters and clinical variables, to assess downstaging and pCR.
  
  
  RESULTS
  Downstaging occurred in 48 patients (31.7 %) and pCR in 19 patients (12.5 %). Univariate and multivariate analysis revealed post-CRT SUVmax as a significant factor for prediction of downstaging, with sensitivity of 60.4 %, specificity of 65.0 %, and accuracy of 55.9 %, for a cutoff value of 3.70. Regarding pCR, post-CRT SUVmax was again found as a significant parameter by univariate and multivariate analysis, with sensitivity of 73.7 %, specificity of 63.7 %, and accuracy of 64.9 %, for a cutoff value of 3.55.
  
  
  CONCLUSIONS
  The results indicate that post-CRT SUVmax independently predicts downstaging and pCR. However, the predictive values of post-CRT SUVmax for tumour response after neoadjuvant CRT are too low in sensitivity and specificity to change the treatment plan for LARC.
authors: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, 809 Madu-1-dong, Ilsandong-gu, Goyang-si, Gyeonggi-do, 410-769, Republic of Korea.
authors: Jong Wan
authors: JW
authors: Kim
authors: Hyun Chul
authors: HC
authors: Kim
authors: Ji Won
authors: JW
authors: Park
authors: Sung Chan
authors: SC
authors: Park
authors: Dae Kyung
authors: DK
authors: Sohn
authors: Hyo Seong
authors: HS
authors: Choi
authors: Dae Yong
authors: DY
authors: Kim
authors: Hee Jin
authors: HJ
authors: Chang
authors: Ji Yeon
authors: JY
authors: Baek
authors: Sun Young
authors: SY
authors: Kim
authors: Seok Ki
authors: SK
authors: Kim
authors: Jae Hwan
authors: JH
authors: Oh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D059248:Chemoradiotherapy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D002272:Carcinoembryonic Antigen; D019788:Fluorodeoxyglucose F18
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