November 25, 2008

Gene Test Could Predict Colon Cancer's Return

TUESDAY, Nov. 25 (HealthDay News) -- U.S. researchers say they've developed a genetic model for predicting the risk of recurrence in patients with early stage colon cancer.

According to a team at the Duke Institute for Genome Science & Policy, the model also predicts colon cancer's sensitivity to chemotherapy and targeted therapy regimens.

The researchers looked for gene expression patterns in 52 samples of early stage colon cancer tumors and correlated those patterns with patient outcomes. They then tested the predictive power of those correlations in two independent data sets from 55 and 73 tumors.

"In our small dataset, we were able to predict which tumors were at risk for recurring with 90 percent accuracy," lead investigator and gastroenterology fellow Dr. Katherine Garman, said in a Duke news release.

The researchers then used the data about gene expression and patient prognosis to study response to several types of cancer therapy.

"Importantly, we found that the traditional chemotherapy given to patients with colon cancer varies considerably in its ability to treat tumors with a high likelihood of cancer recurrence," Garman said. "Using the gene-expression data to guide use, we then identified several other drugs and tested those drugs in our samples. The drugs chosen were novel targeted therapies and anti-inflammatory agents that go after certain cancer cell pathways and had been previously shown to alter colon cancer biology."

Two of the drugs tested by the researchers appeared to "cause significant changes in tumor biology in a laboratory dish, effectively making a high-recurrence-risk tumor into a low-recurrence-risk tumor by altering the genetic makeup," said Garman, who added that these therapies require further testing in clinical trials.

The study was published online this week in the journal Proceedings of the National Academy of Sciences.

"These findings have important implications for individualizing therapy," Garman said. "By examining gene expression in early-stage colon cancer tumors, we have found certain patterns that seem to put some patients at higher risk for recurrence. By identifying these patients up front, we may be able to treat them in a targeted and proactive manner to prevent this recurrence and help them live longer and healthier lives."

More information

The American Cancer Society has more about colorectal cancer.

-- Robert Preidt
SOURCE: Duke Medicine, news release, Nov. 24, 2008
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