MRI helps decisions on lateral nodal disease in rectal cancer

Last Updated: 2019-07-10

By David Douglas

NEW YORK (Reuters Health) - Primary and restaging MRI can help define the risk of lateral local recurrence - and the need for lateral lymph node dissection (LLND) - in patients with low rectal cancer after chemoradiotherapy or radiotherapy, according to a multinational study.

As Dr. Miranda Kusters told Reuters Health by email, "Lateral nodes in rectal cancer need special attention; recognizing them on MRI, irradiating them adequately, and resecting the whole compartment if there is not enough downstaging."

Dr. Kusters of Amsterdam University Medical Centers, in the Netherlands, and colleagues at 12 centers in seven countries reviewed data on 741 patients, including 651 who had undergone chemoradiotherapy or radiotherapy with total mesorectal excision for cT3 or cT4 low rectal cancer. A further 90 also underwent LLND.

A short-axis lateral node size of 7 mm or more on primary MRI resulted in a five-year lateral local recurrence rate of 17.9%.

Nodes that were 7 mm or greater on primary MRI and greater than 4 mm on restaging MRI in the internal iliac compartment had a five-year local recurrence rate of 52.3%. Treatment including LLND was associated with a significantly lower five-year recurrence rate of 8.7%.

Short-axis node size of 7 mm or greater on primary MRI was significantly more common in the internal iliac compartment than in the obturator compartment. In addition, in the obturator nodes, the risk of recurrence was zero with a node size of 6 mm or less on restaging MRI.

Dr. Kusters continued, "Size matters! As lateral nodal disease is uncommon and lateral lymph node dissections preferably need to be performed laparoscopically to adequately identify and spare the hypogastric nerve plexus, centralisation of this procedure is preferred."

In Japan, the researchers note, "it is standard to perform an LLND of both the internal iliac and obturator compartment, irrespective of where the involved node is located."

In the West, said Dr. Kusters, "The next step is a prospective study to lower lateral local recurrence rates" - the so-called LaNoReC trial.

Dr. Alessandro Fichera of the University of North Carolina at Chapel Hill, co-author of an accompanying editorial, told Reuters Health by email, "This is a very important study that represents a crucial first step towards identifying rectal cancer patients at high risk of developing local recurrence and who might benefit from a more aggressive individualized surgical approach."

SOURCE: https://bit.ly/2S90kwV and https://bit.ly/2JtW0V6

JAMA Surg 2019.