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Early Detection Method


RandyW

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WASHINGTON, April 3 (UPI) -- Several new methods that interpret gene expressions and molecular pathways may be breaking down the code of cancer, helping scientists to detect -- and perhaps cure -- the disease in its earliest stages.

In the case of lung cancer, the deadliest cancer in the United States for both men and women, early diagnostic tests such as bronchoscopies usually have low sensitivity, which means they do not pick up cancerous cells effectively. To increase the level of sensitivity, researchers have developed a gene-expression technique that piggybacks off a routine bronchoscopy, a procedure in which a scope is fed through the throat into the lungs.

"I'm excited this novel diagnosis can be added onto an existing procedure," said Avrum Spira, a pulmonary physician at Boston University. Spira spoke at a news conference Monday at the American Association for Cancer Research meeting in Washington.

In a recent study, Spira and colleagues enrolled 152 former smokers who planned to undergo bronchoscopies. The researchers wanted to measure the level of change in gene expression, but first they had to identify the genes that played a role in the cancer. The team used a microarray, a technology that monitors thousands of genes and their products, such as RNA and proteins, to create a broader picture of how the genes interact. The microarray analysis identified a group of 80 genes that could distinguish cancer.

Researchers then used a small brush to collect epithelial cells along the airways of the trachea at the same time as the bronchoscopy.

The first stage of trials for this gene-expression test, also known as a biomarker, resulted in 95-percent sensitivity for detecting early-stage lung cancer in smokers.

Of the 300,000 bronchoscopies done in the United States annually, half will detect cancer and the other half will require further tests, such as biopsies. The airway gene-expression technique could greatly improve diagnosis for lung cancer, which claims 85 percent of patients within five years. Because lung cancer is so difficult to detect in Stage 1, most people discover they have the disease when it has already progressed.

Another major component of the research involves the body's on-off gene switch in response to smoking, Spira said. When exposed to smoke, the epithelial cells in the airways produce a set of enzymes that detoxify the stress. When some smokers develop lung cancer, their bodies may fail to turn on the genes that energize these protective enzymes.

However, Spira told UPI he doesn't know whether the gene-expression test could be applied to the roughly 10 percent of lung-cancer patients who never smoked. Assembling a group of non-smokers on the verge of developing lung cancer would be challenging, Spira said, and so his research has so far focused on smokers.

Earlier detection for colorectal cancer may also be within reach, with the creation of non-invasive blood-screening tests. Currently, most colon-cancer diagnosis is done with fecal occult blood testing, which requires people to collect their own stool samples and bring them to a clinical center. Since such an unpleasant task discourages some patients, a blood test could spot more colorectal-cancer cases.

The blood test targets the Septin 9 gene, a DNA encoder that occurs in the blood plasma of up to 57 percent of patients with colorectal cancer. Researchers developed a test to find this free-floating DNA in the blood. In a recent study of 501 samples, patients tested for Septin 9 had a 50-percent detection rate, already a stronger detection tool than fecal testing, said Catherine Lofton-Day, a researcher for Epigenomics, a molecular-diagnostic company in Seattle. This data was validated by a second, blinded trial of 790 samples.

A blood-based test would not replace other screening tools such as colonoscopies, but it could become part of a routine yearly physical, Lofton-Day told UPI. "It's a simpler test that people would be willing to take when they get their cholesterol tested," she said.

The Septin 9 screening also detected early and late-stage cancer, as well as tumors growing in any part of the body, making it a dependable, non-invasive method.

Other breakthroughs presented at the conference focused on early detection of breast and blood-borne cancer. Anne Lise Borresen-Dale of the Institute for Cancer Research in Oslo, Norway, demonstrated the potential for a blood-based gene-expression test in identifying breast cancer early, and James Morre of Purdue University in Indiana discussed how scientists can detect cancer cells by identifying messenger RNA in the blood.

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