Magnetic resonance imaging assessment of squamous cell carcinoma of the anal canal before and after chemoradiation: can MRI predict for eventual clinical outcome?
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.
Goh
Vicky
V
Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, Middlesex, United Kingdom. vicky.goh@stricklandscanner.org.uk
Gollub
Frank K
FK
Liaw
Jonathan
J
Wellsted
David
D
Przybytniak
Izabela
I
Padhani
Anwar R
AR
Glynne-Jones
Rob
R
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