Restaging MRI After Neoadjuvant Therapy for Low Rectal Cancer and Local Recurrence
Posted: Wednesday, September 11, 2019
Published in JAMA Surgery, a retrospective, multicenter, pooled cohort study, conducted by Atsushi Ogura, MD, of Leiden University Medical Center, the Netherlands, and colleagues in The Lateral Node Study Consortium, examined the role of restaging magnetic resonance imaging (MRI) after chemoradiotherapy or radiotherapy. They focused on the risk of lateral local recurrence in patients with low rectal cancer and probed which patients might benefit from a lateral lymph node dissection.
“In patients with shrinkage of lateral nodes from [a short-axis (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, a lateral lymph node dissection can be avoided,” they concluded. “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.”
The study evaluated 741 patients in 7 countries who underwent operations for cT3 or cT4 low rectal cancer over a 5-year period. Of them, 64.8% were men, and the mean age was 60.4 years.
The investigators found that patients with an SA lateral node size of 7 mm or more on primary MRI had a 5-year lateral local recurrence rate of 17.9% after chemoradiotherapy or radiotherapy with total mesorectal excision. In 28 patients with lateral nodes up to 4 mm on restaging MRI, there were no lateral local recurrences at 3 years. Patients who had nodes that were 7 mm or larger on primary MRI and larger than 4 mm on restaging MRI in the internal iliac compartment had a 5-year lateral local recurrence rate of 52.3%—a rate that was “significantly higher compared with nodes in the obturator compartment of that size,” the investigators said.
“Restaging MRI is important in clinical decision-making in lateral nodal disease,” concluded Dr. Ogura and colleagues.
Disclosure: The study authors’ disclosure information may be found at jamanetwork.com.