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Features on Restaging MRI Associated With Local Recurrence After Neoadjuvant Treatment in Low Rectal Cancer

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Key Points

  • A short-axis lateral node size of ≥ 7 mm on primary MRI was associated with a 5-year lateral local recurrence rate of 17.9% after chemoradiation or radiation therapy with total mesorectal excision.
  • At 3 years, there were no lateral local recurrences in 28 patients (29.2%) with lateral nodes ≤ 4 mm on restaging MRI.

In a retrospective analysis reported in JAMA Surgery, Ogura et al found that persistently enlarged nodes in the internal iliac compartment on restaging magnetic resonance imaging (MRI) after neoadjuvant chemoradiation or radiation therapy for low rectal cancer were associated with high risk of lateral local recurrence, and that such risk was reduced with lateral lymph node dissection.

Study Details

The study involved data from 741 patients from 10 sites in 7 countries who underwent curative intent surgery for cT3 or cT4 low rectal cancer between January 2009 and December 2013. Patients had received chemoradiation or radiation therapy and restaging MRI. The cohort consisted of 651 patients who underwent chemoradiation or radiation therapy with total mesorectal excision and 90 who received chemoradiation or radiation therapy with total mesorectal excision and lateral lymph node dissection.

Key Findings

A short-axis lateral node size of ≥ 7 mm on primary MRI was associated with a 5-year lateral local recurrence rate of 17.9% after chemoradiation or radiation therapy with total mesorectal excision. At 3 years, there were no lateral local recurrences in 28 patients (29.2%) with lateral nodes ≤ 4 mm on restaging MRI. Presence of nodes that were ≥ 7 mm on primary MRI and > 4 mm on restaging MRI in the internal iliac compartment was associated with a 5-year lateral local recurrence rate of 52.3% vs a rate of 9.5% for nodes of this size in the obturator compartment (hazard ratio [HR] = 5.8, P = .003). Compared with chemoradiation or radiation therapy and total mesorectal excision alone, chemoradiation or radiation therapy with total mesorectal excison and lateral lymph node dissection in these persistently enlarged internal iliac nodes resulted in a significantly reduced 5-year lateral local recurrence rate of 8.7% (HR = 6.2, P = .007).

The investigators concluded, “Restaging MRI is important in clinical decision-making in lateral nodal disease. In patients with 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, which occurs in about 30% of cases, lateral lymph node dissection can be avoided. However, persistently enlarged nodes in the internal iliac compartment indicate an extremely high risk of lateral local recurrence, and a lateral lymph node dissection lowered lateral local recurrence in these cases.”

Miranda Kusters, MD, PhD, of the Department of Surgery, Amsterdam University Medical Centers, is the corresponding author for the JAMA Surgery article.

Disclosure: For full disclosures of the study authors, visit jamanetwork.com.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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