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Tumor deposits on MRI in rectal cancer-detection and differentiation from lymph nodes with histopathological correlation

Lundström, Simon LU orcid ; Täckström, Staffan ; Wiklund, Peder ; Haskå, Maja ; Agger, Erik LU orcid ; Nedar, Lennart and Buchwald, Pamela LU (2026) In European Radiology p.1-10
Abstract

OBJECTIVE: Tumor deposits (TDs) are a negative prognostic factor in colorectal cancer, independent of lymph node metastasis (LNM). This study aimed to investigate the ability of pre-operative MRI to identify TDs and differentiate them from LNM in rectal cancer.

MATERIALS AND METHODS: Patients with histopathological N1-N2 rectal cancer with and without TDs who underwent curative-intent primary surgery between 2013 and 2023 were retrospectively included. Three radiologists independently reviewed pre-operative MR images for the presence of TDs and LNM. Histopathology served as the reference standard from which interobserver agreement by Cohen's kappa (κ) was calculated. Unblinded node-to-node comparison of MRI and histopathological... (More)

OBJECTIVE: Tumor deposits (TDs) are a negative prognostic factor in colorectal cancer, independent of lymph node metastasis (LNM). This study aimed to investigate the ability of pre-operative MRI to identify TDs and differentiate them from LNM in rectal cancer.

MATERIALS AND METHODS: Patients with histopathological N1-N2 rectal cancer with and without TDs who underwent curative-intent primary surgery between 2013 and 2023 were retrospectively included. Three radiologists independently reviewed pre-operative MR images for the presence of TDs and LNM. Histopathology served as the reference standard from which interobserver agreement by Cohen's kappa (κ) was calculated. Unblinded node-to-node comparison of MRI and histopathological images was used to identify sources of discrepancies between the modalities. Post hoc analysis stratified on nodal size (> or ≤ 5 mm) was performed.

RESULTS: Eighty-eight patients (50% with TDs on histopathology, 74% male, median age 70 [20-89] years) were included, of whom 27 were excluded due to poor image quality. Agreement between MRI and histopathology (p), both for TD-presence (κ = -0.04) and LNM-presence (κ = 0.16), was low. In the node-by-node comparison, 43 out of 50 pTDs (86%) measured ≤ 5 mm, and 131 of 167 pLNM (78%) measured ≤ 5 mm. In post hoc analysis of smaller (≤ 5 mm) nodules, no pTDs and 3% of pLNM were diagnosed using MRI.

CONCLUSION: MRI demonstrated limited ability in detecting and differentiating TDs and LNM in pre-operative low-risk patients. Diagnostic performance was particularly poor for nodules ≤ 5 mm, which constituted 174 out of 217 (80%) pathological nodular structures.

KEY POINTS: Questions Tumor deposits and lymph node metastasis are important factors for staging rectal cancer, but the ability of pre-operative MRI to detect and differentiate them remains unclear. Findings In low-risk rectal cancer patients treated with primary surgery, tumor deposits and lymph node metastasis are often small (≤ 5 mm) and not detected by MRI. Clinical relevance MRI has a limited ability to identify and differentiate small (≤ 5 mm) tumor deposits and lymph node metastasis in rectal cancer, which must be considered during pre-operative staging and neoadjuvant treatment planning.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
epub
subject
in
European Radiology
pages
1 - 10
publisher
Springer Science and Business Media B.V.
external identifiers
  • pmid:41851526
  • scopus:105033605875
ISSN
0938-7994
DOI
10.1007/s00330-026-12467-x
project
Tumor deposits in rectal cancer: from diagnostics to staging and treatment
language
English
LU publication?
yes
additional info
© 2026. The Author(s).
id
c6e88894-4e34-4fa7-88b3-17ec0fd8492c
date added to LUP
2026-03-22 08:58:24
date last changed
2026-08-20 19:00:58
@article{c6e88894-4e34-4fa7-88b3-17ec0fd8492c,
  abstract     = {{<p>OBJECTIVE: Tumor deposits (TDs) are a negative prognostic factor in colorectal cancer, independent of lymph node metastasis (LNM). This study aimed to investigate the ability of pre-operative MRI to identify TDs and differentiate them from LNM in rectal cancer.</p><p>MATERIALS AND METHODS: Patients with histopathological N1-N2 rectal cancer with and without TDs who underwent curative-intent primary surgery between 2013 and 2023 were retrospectively included. Three radiologists independently reviewed pre-operative MR images for the presence of TDs and LNM. Histopathology served as the reference standard from which interobserver agreement by Cohen's kappa (κ) was calculated. Unblinded node-to-node comparison of MRI and histopathological images was used to identify sources of discrepancies between the modalities. Post hoc analysis stratified on nodal size (&gt; or ≤ 5 mm) was performed.</p><p>RESULTS: Eighty-eight patients (50% with TDs on histopathology, 74% male, median age 70 [20-89] years) were included, of whom 27 were excluded due to poor image quality. Agreement between MRI and histopathology (p), both for TD-presence (κ = -0.04) and LNM-presence (κ = 0.16), was low. In the node-by-node comparison, 43 out of 50 pTDs (86%) measured ≤ 5 mm, and 131 of 167 pLNM (78%) measured ≤ 5 mm. In post hoc analysis of smaller (≤ 5 mm) nodules, no pTDs and 3% of pLNM were diagnosed using MRI.</p><p>CONCLUSION: MRI demonstrated limited ability in detecting and differentiating TDs and LNM in pre-operative low-risk patients. Diagnostic performance was particularly poor for nodules ≤ 5 mm, which constituted 174 out of 217 (80%) pathological nodular structures.</p><p>KEY POINTS: Questions Tumor deposits and lymph node metastasis are important factors for staging rectal cancer, but the ability of pre-operative MRI to detect and differentiate them remains unclear. Findings In low-risk rectal cancer patients treated with primary surgery, tumor deposits and lymph node metastasis are often small (≤ 5 mm) and not detected by MRI. Clinical relevance MRI has a limited ability to identify and differentiate small (≤ 5 mm) tumor deposits and lymph node metastasis in rectal cancer, which must be considered during pre-operative staging and neoadjuvant treatment planning.</p>}},
  author       = {{Lundström, Simon and Täckström, Staffan and Wiklund, Peder and Haskå, Maja and Agger, Erik and Nedar, Lennart and Buchwald, Pamela}},
  issn         = {{0938-7994}},
  language     = {{eng}},
  month        = {{03}},
  pages        = {{1--10}},
  publisher    = {{Springer Science and Business Media B.V.}},
  series       = {{European Radiology}},
  title        = {{Tumor deposits on MRI in rectal cancer-detection and differentiation from lymph nodes with histopathological correlation}},
  url          = {{http://dx.doi.org/10.1007/s00330-026-12467-x}},
  doi          = {{10.1007/s00330-026-12467-x}},
  year         = {{2026}},
}