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
Received 28 October 2008; received in revised form 9 March 2009; accepted 9 March 2009. published online 03 August 2009.
Purpose
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 and Materials
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 (≤3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (≤ 5ml), were, however, significantly associated with an increased pathologic complete response rate.
Conclusion
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.
∗Department of Surgery, Yonsei University Health System, Yonsei University College of Medicine, Seoul, South Korea
†Department of Radiology, Yonsei University Health System, Yonsei University College of Medicine, Seoul, South Korea
‡Department of Pathology, Yonsei University Health System, Yonsei University College of Medicine, Seoul, South Korea
§Department of Radiation Oncology, Yonsei University Health System, Yonsei University College of Medicine, Seoul, South Korea
Reprint requests to: Nam Kyu Kim, M.D., Ph.D., Department of Surgery, Yonsei University College of Medicine, 250 Seongsanno (134 Sinchon-dong), Seodaemun-gu, Seoul, Korea 120-752. Tel: +82-2-2228-2117; Fax: +82-2-313-8289
ABSTRACT