Tumor volume reduction rate measured by magnetic resonance volumetry correlated with pathologic tumor response of preoperative chemoradiotherapy for rectal cancer.
OBJECTIVE
To determine whether the tumor volume reduction rate (TVRR) measured using three-dimensional region-of-interest magnetic resonance volumetry correlates with the pathologic tumor response after preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer.


METHODS
The study included 405 patients with locally advanced rectal cancer (cT3-T4) who had undergone preoperative CRT and radical proctectomy. The tumor volume was measured using three-dimensional region-of-interest magnetic resonance volumetry before and after CRT but before surgery. We analyzed the correlation between the TVRR and the pathologic tumor response in terms of downstaging and tumor regression grade (TRG). Downstaging was defined as ypStage 0-I (ypT0-T2N0M0), and the TRG proposed by Dworak et al. was used.


RESULTS
The mean TVRR was 65.0% +/- 22.3%. Downstaging and complete regression occurred in 167 (41.2%) and 58 (14.3%) patients, respectively. The TVRRs according to ypT classification (ypT0-T2 vs. ypT3-T4), ypN classification (ypN0 vs. ypN1-N2), downstaging (ypStage 0-I vs. ypStage II-III), good regression (TRG 3-4 vs. TRG 1-2), and complete regression (TRG 4 vs. TRG 1-3) were all significantly different (p <.05). When the TVRR was categorized into three groups (<60%, 60-80%, and >80%), the rates of ypT0-T2, ypN0, downstaging, and good regression were all significantly greater for patients with a TVRR of >or=60%, as was the complete regression rate for patients with a TVRR >80% (p <.05).


CONCLUSIONS
The TVRR measured using three-dimensional region-of-interest magnetic resonance volumetry correlated significantly with the pathologic tumor response in terms of downstaging and TRG after preoperative CRT for locally advanced rectal cancer.
Yeo
Seung-Gu
SG
Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
Kim
Dae Yong
DY
Kim
Tae Hyun
TH
Jung
Kyung Hae
KH
Hong
Yong Sang
YS
Chang
Hee Jin
HJ
Park
Ji Won
JW
Lim
Seok-Byung
SB
Choi
Hyo Seong
HS
Jeong
Seung-Yong
SY
D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000601:surgery; D000704:Analysis of Variance; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D012074:Remission Induction / Q000379:methods; D012189:Retrospective Studies; D047368:Tumor Burden / Q000187:drug effects / Q000528:radiation effects