title: Magnetic resonance imaging assessment of squamous cell carcinoma of the anal canal before and after chemoradiation: can MRI predict for eventual clinical outcome?
abstract: OBJECTIVE
  To describe the MRI appearances of squamous cell carcinoma of the anal canal before and after chemoradiation and to assess whether MRI features predict for clinical outcome.
  
  
  METHODS
  Thirty-five patients (15 male, 20 female; mean age 60.8 years) with histologically proven squamous cell cancer of the anal canal underwent MRI before and 6-8 weeks after definitive chemoradiation. Images were reviewed retrospectively by two radiologists in consensus blinded to clinical outcome: tumor size, signal intensity, extent, and TNM stage were recorded. Following treatment, patients were defined as responders by T and N downstaging and Response Evaluation Criteria in Solid Tumors (RECIST). Final clinical outcome was determined by imaging and case note review: patients were divided into (1) disease-free and (2) with relapse and compared using appropriate univariate methods to identify imaging predictors; statistical significance was at 5%.
  
  
  RESULTS
  The majority of tumors were ≤T2 (23/35; 65.7%) and N0 (21/35; 60%), mean size 3.75 cm, and hyperintense (++ to +++, 24/35 patients; 68%). Following chemoradiation, there was a size reduction in all cases (mean 73.3%) and a reduction in signal intensity in 26/35 patients (74.2%). The majority of patients were classified as responders (26/35 (74.2%) patients by T and N downstaging; and 30/35 (85.7%) patients by RECIST). At a median follow-up of 33.5 months, 25 patients (71.4%) remained disease-free; 10 patients (28.6%) had locoregional or metastatic disease. Univariate analysis showed that no individual MRI features were predictive of eventual outcome.
  
  
  CONCLUSIONS
  Early assessment of response by MRI at 6-8 weeks is unhelpful in predicting future clinical outcome.
authors.affiliation: Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, Middlesex, United Kingdom. vicky.goh@stricklandscanner.org.uk
authors.forename: Vicky
authors.initials: V
authors.lastname: Goh
authors.forename: Frank K
authors.initials: FK
authors.lastname: Gollub
authors.forename: Jonathan
authors.initials: J
authors.lastname: Liaw
authors.forename: David
authors.initials: D
authors.lastname: Wellsted
authors.forename: Izabela
authors.initials: I
authors.lastname: Przybytniak
authors.forename: Anwar R
authors.initials: AR
authors.lastname: Padhani
authors.forename: Rob
authors.initials: R
authors.lastname: Glynne-Jones
mesh_terms: D001003:Anal Canal / Q000473:pathology; D000704:Analysis of Variance; D001005:Anus Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy / Q000556:secondary; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D009367:Neoplasm Staging; D012189:Retrospective Studies; D016896:Treatment Outcome; D047368:Tumor Burden