7/29/2019 MRI predicts curative resection in rectal cancer - Ed Fitzgerald - Surgeons News

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in a nutshell

second opinion

the verdictColorectal cancer remains the

second commonest cause of

cancer death. Curative therapy

for rectal cancer relies on the

technically demanding total

mesorectal excision (TME).

Histopathological examina-

tion of surgical specimens

shows a strong correlation

between clear circumferential

resection margins and risk of

local recurrence. Pre-operative

radio- or chemoradiotherapy

decreases the rate of local

MRI predicts curative resection in rectal cancerMERCURY Study Group. Diagnostic accuracy of preoperative magnetic resonance imaging in predicting curative

resection of rectal cancer: prospective observational study. BMJ2006; 333: 779.

Three hundred and forty nine

patients underwent surgery

having clear resection margins

predicted by MRI. Of these,

327 had clear margins in the

surgical specimen (94%, 91-

96% CI). Three hundred and

fty four patients had clear

margin on histopathology. Of

these, 327 were predicted by

MRI (92%, 89-95% CI).

This study conrms our belief

that MRI is the gold standard

staging investigation for rectal

cancers. The majority of UK

centres have already adopted

this staging tool for predicting

a surgically clear margin.

A number of patients in this

investigation had a predicted

involved margin on MRI but

MRI should form part of

the pre-operative MDT

decision-making process

for treatment of rectal

cancer

It is the best investigation

for predicting tumour

involvement at the resec-

tion margin and is more

accurate than digital rectal

examination

More work needs to be

done to understand the

affect of pre-operative

therapy on the subsequent

tissue appearances of MRI

investigations.

Edward Fitzgerald

edwardftzgerald@doctors.

org.uk

Austin G Acheson

Austin.Acheson@nottingham.

ac.uk

recurrence by reducing tumour

proximity to these margins and

therefore increasing the likeli-

hood of complete excision.

This paper demonstrates the

use of MRI in the pre-operative

assessment of the involve-

ment of margins and therefore

enable better planning of

preoperative therapy and sub-

sequent surgery.

Eleven colorectal units

recruited 408 consecutive

patients with rectal cancer.

The accuracy of pre-operative

MRI to predict a curative resec-

tion based on presence or

absence of tumour at the resec-

tion margins was assessed.

Three hundred and eleven

patients underwent primary

surgery. The prediction ac-

curacy for a clear margin was

91% (88-94% CI). In those

who underwent pre-operative

radio- or chemoradiotherapy,

the accuracy was 77% (69-

86% CI).

clear margins on histopathol-

ogy but this certainly reects

the benets of aggressive pr-

eoperative oncological therapy

on tumour shrinkage.

The study does have limita-

tions and perhaps the most

alarming is that approximately

40% (22/54) of patients with

involved margins had not been

predicted by preoperative MRI.

However, 50% of these

patients had intraoperative

perforations due to presumed

technically difcult surgery

and involved margins could

obviously not be predicted in

such cases. Identication of

involved lymph nodes within

1mm of the resection margin

accounted for the majority

of the remainder rather than

direct spread of

the tumour.

However, the impact on recur-

rence of this special sub-group

has not yet been established.

It is heartening to see that

such good results for surgical

excision together with consist-

ent imaging and histopatho-

logical interpretation can be

achieved in a reproducible

fashion across many centres.

This does much to support

the further development of

optimal cancer treatment

through standardisation and

quality control by way of dedi-

cated workshops promoting

best-practice, whatever the

specialty.

16 surgeonsnews n analysis n april 2007 6.2