title: Good and complete responding locally advanced rectal tumors after chemoradiotherapy: where are the residual positive nodes located on restaging MRI?
abstract: Aim of this study was to evaluate the distribution of persistent mesorectal lymph node metastases on restaging MRI in patients with a good or complete response of their primary tumor (ypT0-2) after CRT for locally advanced rectal cancer.
  
  
  
  Two hundred and twenty eight locally advanced rectal cancer patients underwent CRT, which resulted in a good response (downstaging to yT0-2) in 144 patients. Forty-nine patients were excluded (no surgery/insufficient follow-up or lacking lesion-by-lesion histology results). This resulted in a final study group of 95 yT0-2 patients. For the patients with a yN(+)-status, a detailed lesion-by-lesion comparison between restaging MRI and histology was performed to evaluate the characteristics and distribution of the individual N(+)-nodes.
  
  
  
  7/95 patients (7%) had a yT0-2N(+) status (11/880 (1%) N(+) nodes): no N(+) were found below the tumor level, 55% of the N(+) nodes were located at the level of the tumor, and 45% proximal to the tumor (at a median distance of 1.4 cm above the tumor level). In axial plane, 82% of the nodes were located at the ipsilateral circumference of the tumor, at a median distance of 0.9 cm from the tumor/rectal wall.
  
  
  
  The incidence of persistent metastatic mesorectal nodes after CRT in patients with a good tumor response after CRT is very low. No N(+) nodes are found below the tumor level. All N(+) nodes are located at the level of or proximal to the primary tumor, of which the majority very close to the tumor/lumen.
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Luc A
authors.initials: LA
authors.lastname: Heijnen
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands. d.lambregts@nki.nl.|Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands. d.lambregts@nki.nl.
authors.forename: Doenja M J
authors.initials: DM
authors.lastname: Lambregts
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Max J
authors.initials: MJ
authors.lastname: Lahaye
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.|Department of Surgery, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Milou H
authors.initials: MH
authors.lastname: Martens
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Thiemo J A
authors.initials: TJ
authors.lastname: van Nijnatten
authors.affiliation: Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai, China.
authors.forename: Sheng-Xiang
authors.initials: SX
authors.lastname: Rao
authors.affiliation: Department of Pathology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Riedl
authors.affiliation: Department of Radiation Oncology, Maastro Clinic, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Buijsen
authors.affiliation: Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Monique
authors.initials: M
authors.lastname: Maas
authors.affiliation: Department of Surgery, The Netherlands Cancer Institute, Amsterdam, The Netherlands.|GROW School for Oncology and Developmental Biology, Maastricht, The Netherlands.
authors.forename: Geerard L
authors.initials: GL
authors.lastname: Beets
authors.affiliation: Department of Radiology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.|GROW School for Oncology and Developmental Biology, Maastricht, The Netherlands.
authors.forename: Regina G H
authors.initials: RG
authors.lastname: Beets-Tan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012189:Retrospective Studies
keywords: Lymph node staging; MRI; Rectal cancer; Response assessment
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