Extended total mesorectal excision in locally advanced rectal cancer (T4a) and the clinical role of MRI-evaluated neo-adjuvant downstaging.
OBJECTIVE
To compare the clinical ability of MRl taken before and after neo-adjuvant treatment in locally advanced rectal cancer (LARC) to predict the necessary extension of TME (ETME) and the possibility to achieve a R0 resection.


METHODS
Prospective registration of 92 MRI evaluated T4a cancers undergoing elective surgery between 2002 and 2007 in a tertiary referral centre for multimodal treatment of rectal cancer.


RESULTS
MRI identified patients in need of neo-adjuvant treatment and predicted T-downstaging in 10% and N-downstaging in 59%. Seventy-nine percent R0 resections, 18% R1 and 3% R2 were obtained after ETME in 95% of the patients and TME in the rest. Higher tumour regression grade (TRG) was achieved in higher ypT-stage (P < 0.01). Preoperative chemo radiotherapy resulted in that more patients obtained TRG1-3 compared to those receiving radiotherapy (79% vs. 57%, P = 0.02). The pelvic wall was the area of failure in 70% of the R1 resections. Tumour cells outside the mesorectal fascia scattered within fibrosis was found in 18 TRG2-3 among 33 ypT4 tumours (55%).


CONCLUSIONS
MRl cannot discriminate tumour within fibrosis. Therefore, if a R0 resection is the goal, we advocate optimal surgery in accordance with the pre-treatment MRI. Post treatment MRI is a poor predictor of final histology and should not be relied upon to guide the extent of surgical resection. The study has initiated a new approach to histopathological classification of the removed specimen where we introduce a MRI assisted technique for investigating the areas at risk outside the mesorectal fascia in the specimen.
Larsen
S G
SG
Department of Surgical Oncology, the Norwegian Radium Hospital, Rikshospitalet University Hospital, Oslo, Norway. stein.larsen@radiumhospitalet.no
Wiig
J N
JN
Emblemsvaag
H L
HL
Grøholt
K K
KK
Hole
K H
KH
Bentsen
A
A
Dueland
S
S
Vetrhus
T
T
Giercksky
K-E
KE
D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery*; D017024:Chemotherapy, Adjuvant; D005260:Female; D005355:Fibrosis / Q000150:complications / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging / Q000379:methods; D011446:Prospective Studies; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000473:pathology* / Q000601:surgery*