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Int J Colorectal Dis. 2016 Jun;31(6):1157-62. doi: 10.1007/s00384-016-2576-8. Epub 2016 Apr 7.

Nodal staging in rectal cancer: why is restaging after chemoradiation more accurate than primary nodal staging?

Author information

1
Department of Radiology, Maastricht University Medical Center, Maastricht University, PO Box 5800, 6202, Maastricht, The Netherlands.
2
Department of Surgery, Maastricht University Medical Center, Maastricht University, PO Box 5800, 6202, Maastricht, The Netherlands.
3
Department of Radiology, Maastricht University Medical Center, Maastricht University, PO Box 5800, 6202, Maastricht, The Netherlands. moniquemaas@live.nl.
4
Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands. moniquemaas@live.nl.
5
GROW-School for Oncology and Developmental Biology, PO Box 616, 6200, Maastricht, The Netherlands. moniquemaas@live.nl.
6
Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
7
GROW-School for Oncology and Developmental Biology, PO Box 616, 6200, Maastricht, The Netherlands.
8
Department of Epidemiology, Maastricht University Medical Center, Maastricht University, PO Box 5800, 6202 AZ, Maastricht, The Netherlands.
9
Department of Pathology, Zuyderland Medical Centre, PO Box 5500, 6130 MB, Sittard, The Netherlands.
10
Department of Surgery, The Netherlands Cancer Institute, Amsterdam, The Netherlands.

Abstract

PURPOSE:

This study aims to explore the influence of chemoradiation treatment (CRT) on rectal cancer nodes and to generate hypotheses why nodal restaging post-CRT is more accurate than at primary staging.

METHODS:

Thirty-nine patients with locally advanced rectal cancer underwent MRI pre- and post-CRT. All visible mesorectal nodes were measured on a 3D T1-weighted gradient echo (3D T1W GRE) sequence with 1-mm(3) voxels and matched between pre- and post-CRT-MRI and with histology by lesion-by-lesion matching. Change in number and size of nodes was compared between pre- and post-CRT-MRI. ROC curves were constructed to assess diagnostic performance of size.

RESULTS:

Eight hundred ninety-five nodes were found pre-CRT: 44 % disappeared and 40 % became smaller post-CRT. Disappearing nodes were initially significantly smaller than nodes that remained visible post-CRT: 2.9 mm vs. 3.8 mm. cN+ stage was predicted in 97 % pre-CRT and 36 % of patients had ypN+ post-CRT. ypN+ patients had significantly larger nodes than ypN0 patients both pre- and post-CRT. Optimal size cutoff for post-CRT ypN stage prediction was 2.5 mm (area under the curve (AUC) of 0.78) at MRI.

CONCLUSIONS:

After CRT, most lymph nodes become smaller, and many disappear. Size predicts disappearance and node positivity. Together with a low prevalence of ypN+, this can explain the higher accuracy of nodal staging after CRT than in a primary staging setting, possibly of use when considering organ-preserving strategies after CRT.

KEYWORDS:

Chemoradiation; Histopathology; Nodal staging; Rectal cancer; Response

PMID:
27055660
PMCID:
PMC4867151
DOI:
10.1007/s00384-016-2576-8
[Indexed for MEDLINE]
Free PMC Article

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