Can magnetic resonance imaging predict circumferential margins and TNM stage in rectal cancer?
BACKGROUND
This study was designed to assess whether preoperative magnetic resonance imaging scans were able to predict 1) pathologic tumor and node stage, and 2) those patients with a pathologically clear circumferential resection margin.


METHODS
Patients with histologically proven carcinoma of the rectum were staged preoperatively using magnetic resonance imaging. Histologic specimens from patients undergoing mesorectal excision were reported according to the Royal College of Pathologists minimum dataset. Agreement between radiologic staging of tumor, local lymph nodes and circumferential resection margin involvement, and pathologic reporting was assessed by means of the Kappa statistic.


RESULTS
After exclusions (10 radiotherapy, 3 failed scans, 10 no surgery, 9 local surgery), 40 patients remained. Magnetic resonance imaging correctly staged the tumor in 20 patients, understaged in 12, and overstaged in 8. Statistically, there was poor correlation between pathologic and radiologic tumor staging (Kappa, 0.18; 95 percent confidence interval, -0.13 to 0.42). Magnetic resonance imaging correctly staged node status in 27 patients, overstaged in 9, and understaged in 4. Statistically, there was poor correlation between pathologic and radiologic node staging (Kappa, 0.38; 95 percent confidence interval, 0.08-0.64). Magnetic resonance imaging correctly reported the status of the circumferential resection margin in 39 patients and understaged 1. Statistically, there was good correlation between pathologic and radiologic reporting of circumferential resection margin involvement (Kappa, 0.66; 95 percent confidence interval, 0.03-1).


CONCLUSIONS
Preoperative magnetic resonance imaging scans provide poor predictive data as to subsequent pathologic tumor and node stage. Preoperative magnetic resonance imaging does produce reliable prediction of clear circumferential resection margins and provides valuable information in assessing whether patients can proceed to surgery without the need for preoperative radiotherapy.
Department of Surgery, Salisbury District Hospital, Salisbury, Wilts, United Kingdom. gbr1911@yahoo.co.uk
Graham
G
Branagan
Helen
H
Chave
Clare
C
Fuller
Shaun
S
McGee
Derek
D
Finnis
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000473:pathology* / Q000601:surgery; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012004:Rectal Neoplasms / Q000473:pathology* / Q000601:surgery; D012680:Sensitivity and Specificity