January 5, 2007
Promising Genetic Test for Non-small-cell Lung CancerTopics: Medicine
Lung cancer is the world's top cancer killer, with about 175,000 new cases and 162,000 deaths in the United States each year. In Canada last year, there were an estimated 22,700 new cases and 19,300 deaths. However, a promising new test developed by scientists in Taiwan has the potential to be extremely helpful in early diagnosis in lung cancer, allowing for both earlier and more effective treatment. The test offers further proof that understanding genetic signatures may be helpful in how we treat patients, how to avoid treating some patients, and possibly how to pinpoint those patients who may not respond to current drugs and would be better off trying an experimental therapy: :
The current staging system for non-small-cell lung cancer is inadequate for predicting treatment outcomes, whereas molecular methods appear valuable in estimating prognosis and in determining therapy, Pan-Chyr Yang, M.D., Ph.D., of the National Taiwan University Hospital, and colleagues, wrote in the Jan. 4 issue of the New England Journal of Medicine.The researchers say that this report reflects the maturation of the first phase of lung-cancer genomics, which has been based on stored tissue and clinical charts. They believe that the field is now poised to begin its next phase - prospective trials of adjuvant chemotherapy in patients with early lung cancer who are selected because they have a high risk of relapse or metastasis according to the molecular signature identified in this study or by others.
In a gene profiling study, the researchers used computer-generated random numbers to assign 185 frozen specimens for microarray analysis, real-time reverse-transcriptase polymerase chain reaction (RT-PCR) analysis, or both.
Next, they studied gene expression in frozen specimens of lung cancer tissue from 125 randomly selected patients who had undergone surgical resection for non-small-cell lung cancer between 1999 and 2003. The specimens were evaluated for the level of expression and for survival.
The specimens represented a mixture of tumor types and stages. Of the 125 specimens, 60 were adenocarcinomas, 52 were squamous-cell carcinomas, and 13 were other types.
Of an original 672 genes associated with invasive activity, the researchers identified 16 that correlated with increased survival (four) or decreased (12). From this, they developed a score that discriminated between high and low risk of death or recurrence.
To develop a gene-expression model to predict treatment outcome, they selected five genes for RT-PCR and decision-tree analysis. They found that the presence of the five-gene signature was an independent predictor of relapse-free and overall survival.
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Posted by Richard at January 5, 2007 7:24 AM
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