Tumor perfusion increases during hypofractionated short-course radiotherapy in rectal cancer: Sequential perfusion-CT findings

Janssen, Marco H.M.; Aerts, Hugo J.W.L.; Kierkels, Roel G.J.; Backes, Walter H.; Öllers, Michel C.; Buijsen, Jeroen; Lambin, Philippe; Lammering, Guido

doi:10.1016/j.radonc.2009.12.013

« Previous Next »Radiotherapy & Oncology
Volume 94, Issue 2 , Pages 156-160, February 2010

Tumor perfusion increases during hypofractionated short-course radiotherapy in rectal cancer: Sequential perfusion-CT findings

Marco H.M. Janssen
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
- Corresponding author. Address: Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), GROW-School for Oncology and Developmental Biology, Dr. Tanslaan 12, 6201 BN Maastricht, Box 1588, Maastricht, The Netherlands.
Hugo J.W.L. Aerts
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
Roel G.J. Kierkels
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
Walter H. Backes
- Department of Radiology, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
Michel C. Öllers
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
Jeroen Buijsen
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
Philippe Lambin
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
- These authors contributed equally to this paper.
Guido Lammering
- Department of Radiation Oncology (MAASTRO), Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
- These authors contributed equally to this paper.

Received 16 October 2009; received in revised form 13 December 2009; accepted 20 December 2009. published online 18 January 2010.

Abstract

Purpose

The purpose of this study was to investigate perfusion of rectal tumors and to determine early responses to short-course hypofractionated radiotherapy (RT).

Material and methods

Twenty-three rectal cancer patients were included, which underwent perfusion-CT imaging before (pre-scan) and after treatment (post-scan). Contrast-enhancement was measured in tumor and muscle tissues and in the external iliac artery. Perfusion was quantified with three pharmacokinetic parameters: K^trans, v_e and v_p. Perfusion differences between tumor and normal tissue and changes of the pharmacokinetic parameters between both scans were evaluated.

Results

The median tumors K^trans values increased significantly from the pre-scan (0.36±0.11 (min⁻¹)) to the post-scan (0.44±0.13 (min⁻¹)) (p<0.001). Also, histogram analysis showed a shift of tumor voxels from lower K^trans values towards higher K^trans values. Furthermore, the median K^trans values were significantly higher for tumor than for muscle tissue on both the pre-scan (0.10±0.05 (min⁻¹), p<0.001) and the post-scan (0.10±0.04 (min⁻¹), p<0.001). In contrast, no differences between tumor and muscle tissues were found for v_e and v_p. Also, no significant differences were observed for v_e and v_p between the two pCT-imaging time-points.

Conclusions

Hypofractionated radiotherapy of rectal cancer leads to an increased tumor perfusion as reflected by an elevated K^trans, possibly improving the bioavailability of cytotoxic agents in rectal tumors, often administered early after radiotherapy treatment.

Keywords: Perfusion-CT, Pharmacokinetic modeling, Rectal cancer, Tumor perfusion, Short-course hypofractionated radiotherapy