title: Diffusion-weighted magnetic resonance imaging for predicting the response of rectal cancer to neoadjuvant concurrent chemoradiation.
abstract: OBJECTIVE
  To evaluate the clinical value of diffusion-weighted magnetic resonance imaging (DW-MRI) in predicting the response of rectal cancer to neoadjuvant chemoradiation.
  
  
  METHODS
  This prospective study was approved by our institutional review board, and informed consent was obtained from each patient. Fifteen patients (median age 56 years) with locally advanced rectal cancer were treated in our hospital from June 2006 to December 2007. All patients were stage IIIB-C according to the results of MRI and endorectal ultrasound examinations. All patients underwent pelvic irradiation with 45 Gy/25 fx per 35 days. The concurrent chemotherapy regimen consisted of capecitabine 625 mg/m², bid (Monday-Friday), and oxaliplatin 50 mg/m², weekly. The patients underwent surgery 5-8 wk after the completion of neoadjuvant therapy. T downstaging was defined as the downstaging of the tumor from cT3 to ypT0-2 or from cT4 to ypT0-3. Good regression was defined as TRG 3-4, and poor regression was defined as TRG 0-2. Diffusion-weighted magnetic resonance images were obtained prior to and weekly during the course of neoadjuvant chemoradiation, and the apparent diffusion coefficient (ADC) values were calculated from the acquired tumor images.
  
  
  RESULTS
  Comparison with the mean pretreatment tumor ADC revealed an increase in the mean tumor ADC during the course of neoadjuvant chemoradiation, especially at the 2(nd) week (P = 0.004). We found a strong negative correlation between the mean pretreatment tumor ADC and tumor regression after neoadjuvant chemoradiation (P = 0.021). In the T downstage and tumor regression groups, we found a significant increase in the mean ADC at the 2(nd) week of neoadjuvant therapy (P = 0.011; 0.004).
  
  
  CONCLUSIONS
  DW-MRI might be a valuable clinical tool to help predict or assess the response of rectal cancer to neoadjuvant chemoradiation at an early timepoint.
authors.affiliation: Gang Cai, Ji Zhu, Xue-Jun Ma, Zhen Zhang, Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Cai
authors.forename: Ye
authors.initials: Y
authors.lastname: Xu
authors.forename: Ji
authors.initials: J
authors.lastname: Zhu
authors.forename: Wei-Lie
authors.initials: WL
authors.lastname: Gu
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Ma
authors.forename: San-Jun
authors.initials: SJ
authors.lastname: Cai
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000628:therapy; D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000628:therapy; D055815:Young Adult
keywords: Apparent diffusion coefficient; Diffusion-weighted magnetic resonance imaging; Locally advanced rectal cancer; Neoadjuvant chemoradiation
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