Lateral Nodal Features on Restaging Magnetic Resonance Imaging Associated With Lateral Local Recurrence in Low Rectal Cancer After Neoadjuvant Chemoradiotherapy or Radiotherapy

Atsushi Ogura, Tsuyoshi Konishi, Geerard L. Beets, Chris Cunningham, Julio Garcia-Aguilar, Henrik Iversen, Shigeo Toda, In Kyu Lee, Hong Xiang Lee, Keisuke Uehara, Peter Lee, Hein Putter, Cornelis J. H. van de Velde, Harm J. T. Rutten, Jurriaan B. Tuynman, Miranda Kusters*, Roel Hompes, Takashi Akiyoshi, Dennis Schaap, Grard A. NieuwenhuijzenHenrik Iversen, Anna Martling, Maxime J. M. van der Valk, Elma Meershoek-Klein-Kranenbarg, Julio Garcia-Aguilar, Ivana M. Blazic, Marc J. Gollub, Toshisada Aiba, Arend G. J. Aalbers, Marit E. van der Sande, Regina H. Beets-Tan, Monique Maas, Katarzyna Jozwiak, Chris Cunningham, Margaret Betts, James Moore, Michelle Thomas, Tarik Sammour, Tim Wells, Michael J. Solomon, Kilian G. Brown, Daeyoun David Won, Min Ki Kim, Soon Nam Oh, Moon Hyung Choi, Hiroya Kuroyanagi, Yutaka Hanaoka, Kenji Tomizawa, Lateral Node Study Consortium

*Corresponding author for this work

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Abstract

Key PointsQuestionWhat is the role of restaging magnetic resonance imaging (MRI) after chemoradiotherapy or radiotherapy, and which specific patients might benefit from a lateral lymph node dissection (LLND)? FindingsIn this multicenter pooled cohort study including 741 patients with low rectal cancer after chemoradiotherapy or radiotherapy, shrinkage of lateral nodes from a short-axis node size of 7 mm or greater on primary MRI to a short-axis node size of 4 mm or less on restaging MRI abolished the risk of lateral local recurrence (LLR). However, in persistently enlarged nodes (greater than 4 mm) in the internal iliac compartment on restaging MRI, the risk of LLR was high, and an LLND lowered this risk significantly. MeaningPersistently enlarged nodes in the internal iliac compartment indicate a high risk of LLR, and an LLND should be seriously considered in these patients.

This cohort study investigates the factors on primary and restaging magnetic resonance imaging that are associated with lateral local recurrence in low rectal cancer after chemoradiotherapy or radiotherapy and to formulate specific guidelines on which patients might benefit from a lateral lymph node dissection.

ImportancePreviously, it was shown in patients with low rectal cancer that a short-axis (SA) lateral node size of 7 mm or greater on primary magnetic resonance imaging (MRI) resulted in a high lateral local recurrence (LLR) rate after chemoradiotherapy or radiotherapy ([C]RT) with total mesorectal excision (TME) and that this risk was lowered by a lateral lymph node dissection (LLND). The role of restaging MRI after (C)RT with regard to LLR risk and which specific patients might benefit from an LLND is not fully understood. ObjectiveTo determine the factors on primary and restaging MRI that are associated with LLR in low rectal cancer after (C)RT and to formulate specific guidelines on which patients might benefit from an LLND. Design, Setting, and ParticipantsIn this retrospective, multicenter, pooled cohort study, patients who underwent surgery for cT3 or cT4 low rectal cancer with a curative intent from 12 centers in 7 countries from January 2009 to December 2013 were included. All patients' MRIs were rereviewed according to a standardized protocol, with specific attention to lateral nodal features. The original cohort included 1216 patients. For this study, patients who underwent (C)RT and had a restaging MRI were selected, leaving 741 for analyses across 10 institutions, including 651 who underwent (C)RT with TME and 90 who underwent (C)RT with TME and LLND. Main Outcomes and MeasuresThe main purpose was to identify the factors on primary and restaging MRI associated with LLR after (C)RT with TME. Whether high-risk patients might benefit in terms of LLR reduction from an LLND was also studied. ResultsOf the 741 included patients, 480 (64.8%) were male, and the mean (SD) age was 60.4 (12.0) years. An SA lateral node size of 7 mm or greater on primary MRI resulted in a 5-year LLR rate of 17.9% after (C)RT with TME. At 3 years, there were no LLRs in 28 patients (29.2%) with lateral nodes that were 4 mm or less on restaging MRI. Nodes that were 7 mm or greater on primary MRI and greater than 4 mm on restaging MRI in the internal iliac compartment resulted in a 5-year LLR rate of 52.3%, significantly higher compared with nodes in the obturator compartment of that size (9.5%; hazard ratio, 5.8; 95% CI, 1.6-21.3; P=.003). Compared with (C)RT with TME alone, treatment with (C)RT with TME and LLND in these unresponsive internal nodes resulted in a significantly lower LLR rate of 8.7% (hazard ratio, 6.2; 95% CI, 1.4-28.5; P=.007). Conclusions and RelevanceRestaging MRI is important in clinical decision making in lateral nodal disease. In patients with shrinkage of lateral nodes from an SA node size of 7 mm or greater on primary MRI to an SA node size of 4 mm or less on restaging MRI, which occurs in about 30% of cases, LLND can be avoided. However, persistently enlarged nodes in the internal iliac compartment indicate an extremely high risk of LLR, and an LLND lowered LLR in these cases.

Original languageEnglish
Article number192172
Pages (from-to)1-8
Number of pages8
JournalJAMA Surgery
Volume154
Issue number9
DOIs
Publication statusPublished - Sept 2019

Keywords

  • TOTAL MESORECTAL EXCISION
  • PREOPERATIVE CHEMORADIOTHERAPY
  • DISSECTION
  • SURVIVAL
  • INVOLVEMENT
  • JAPAN

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