Tumor volume changes assessed by three-dimensional magnetic resonance volumetry in rectal cancer patients after preoperative chemoradiation: the impact of the volume reduction ratio on the prediction of pathologic complete response.
OBJECTIVE
The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT).


METHODS
A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG).


RESULTS
There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate.


CONCLUSIONS
More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.
Kang
Jeong Hyun
JH
Department of Surgery, Yonsei University Health System, Yonsei University College of Medicine, Seoul 120-752, South Korea.
Kim
Young Chul
YC
Kim
Hyunki
H
Kim
Young Wan
YW
Hur
Hyuk
H
Kim
Jin Soo
JS
Min
Byung Soh
BS
Kim
Hogeun
H
Lim
Joon Seok
JS
Seong
Jinsil
J
Keum
Ki Chang
KC
Kim
Nam Kyu
NK
D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy / Q000379:methods; D051517:Digital Rectal Examination; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D020266:Radiotherapy, Conformal; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D012074:Remission Induction; D047368:Tumor Burden