Last Updated: August 16, 2005



NEW YORK (Reuters Health) - Gene expression profiling of primary
colorectal cancer tumors could improve the accuracy of traditional
methods for predicting lymph node metastases, a new study shows.


While computed tomography and endosonography are now used in patients
with rectal cancer before surgery to identify metastatic lymph nodes,
their predictive value is limited, Dr. Roland S. Croner of the
University of Erlangen in Germany and colleagues write. For colon
cancer patients, potentially affected lymph nodes are examined at the
time of surgery, and their status is identified after surgery using
histopathology.

Dr. Croner and his team investigated the possibility that gene
expression data from the primary tumor obtained with oligonucleotide
microarrays could be used to improve the predictive value of these
techniques.

They looked at 66 patients treated surgically for colorectal cancer,
25 of whom had lymph node metastases. Six different statistical
techniques were used to analyze expression patterns of a selected
cluster of genes, including several previously described molecular
markers.

"This cluster included genes involved in cellular adhesion, the cell
cycle, cytoskeleton, and migration," the researchers note in the July
15 issue of Cancer.

Positive prediction rates for lymph node metastasis using traditional
parameters ranged from 53% to 61%, while combining this information
with microarray data resulted in prediction rates between 65% and
70%, Dr. Croner and colleagues found.

The authors caution that collection techniques, tissue preparation
and statistical methods all have an effect on microarray analysis
results, and note that using "bundling" to help apply several
different algorithms can prevent "over-optimistic estimations."

Gene expression profiling could one day be used clinically to help
determine whether lymph node dissection is necessary, and could
potentially allow for less radical surgery if results could be
obtained from tissue biopsied before surgery, they write.

For now, however, "Based on our findings, more patients need to be
evaluated prospectively to improve the gene-expression-based
prediction rates for lymph node metastasis in colorectal cancer," the
researchers conclude.





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