How accurate is magnetic resonance imaging in restaging rectal cancer in patients receiving preoperative combined chemoradiotherapy?
OBJECTIVE
Preoperative combined chemoradiotherapy is currently the main neoadjuvant therapy used to treat locally advanced middle and low rectal adenocarcinoma. A restaging work-up with magnetic resonance imaging was hoped to provide information about the effects related to combined chemoradiotherapy. The goal was to evaluate the correlation between pathologically verified tumor stages and clinical stages predicted by magnetic resonance imaging after combined chemoradiotherapy.


METHODS
Between August 2000 and June 2003, 50 patients with biopsy-proven middle and lower rectal adenocarcinoma, with initial stage T3-T4 or N+, M0, were recruited in this series. Pelvic magnetic resonance imaging was used to stage the tumor before and after combined chemoradiotherapy. A protocol of the standard external radiation dose and oral combined uracil and 5-fluorouracil plus leucovorin was used. The results of magnetic resonance imaging restaging after combined chemoradiotherapy were correlated with the pathologic staging.


RESULTS
The overall predictive accuracy in T stage was 52 percent, whereas overstaging and understaging occurred in 38 percent and 10 percent of patients, respectively. Most of the inaccurate T staging was a result of the overstaging of superficial tumors (T0-T2). In N stage, accurate staging was noted in 68 percent of all patients, whereas 24 percent were overstaged and 8 percent were understaged.


CONCLUSIONS
In restaging irradiated tumors, magnetic resonance imaging had the accuracy of 52 percent in T stage and 68 percent in N stage. Poor agreement between post-combined chemoradiotherapy magnetic resonance imaging and pathologic staging was observed in both T (k = 0.017) and N (k = 0.031) stages. Most of the inaccuracy in both T and N stages was caused by overstaging. The problem with magnetic resonance imaging was believed to be that it could not completely differentiate fibrosis from viable residual tumors.
Chen
Chien-Chih
CC
Division of Colon and Rectal Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan.
Lee
Rheun-Chuan
RC
Lin
Jen-Kou
JK
Wang
Ling-Wei
LW
Yang
Shung-Haur
SH
D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging / Q000379:methods* / Q000592:standards; D011237:Predictive Value of Tests; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014498:Uracil / Q000008:administration & dosage
D014498:Uracil; D005472:Fluorouracil