Scientists have developed a test for the early diagnosis of lung cancer. They hope the analysis of which genes are switched on and off in cells lining the airways leading to the lungs can be used to diagnose patients sooner and make treatments more effective.
Lung cancer is the most deadly form of the disease. In Britain it is the most common cancer in men and the third most common in women. In 2002 about 37,700 new cases were recorded and nearly 29,000 deaths.
Part of the reason it is so lethal is that the disease is often diagnosed late. Patients frequently die shortly after learning they have contracted the disease. Only one fifth of patients are alive one year after diagnosis of the disease, which kills 92% within five years. The vast majority of lung cancer sufferers are smokers.
Avrum Spira and his team at Boston University in Massachusetts examined lung tissue collected from 129 current or former smokers.
All were undergoing normal lung examination tests for detecting suspected lung cancer, that involve scraping cells from the inner lining of their airways and examining them under a microscope to look for abnormalities.
The team examined the expression of 80 genes in the cells. And by waiting until the patients were given the a definitive "all clear" or lung cancer diagnosis they identified a pattern of gene expression or "biomarker" that was consistently associated with a cancer diagnosis. The team validated their method with a further 35 samples from patients at five hospitals. "Our biomarker had [about] 90% sensitivity for stage 1 cancer across all subjects," they wrote in the current issue of Nature Medicine. Combining this with traditional techniques that look for abnormal features of the cells, the sensitivity increased to 90%. On their own these traditional techniques have a sensitivity of around 30% in early stage cancer.
If the technique proves successful in further tests it could be streamlined into a "DNA chip" that gives a rapid readout of which genes are active in cells taken from the patient. This could lead to much earlier diagnosis of lung cancers which would allow doctors to start treatment earlier and give patients a better chance of surviving the disease. It would also give an earlier incentive for smokers to give up. "Our biomarker might be useful as a screening tool for lung cancer among healthy smokers," the authors wrote.
Smoking has numerous other health effects such as greatly increasing the risk of heart disease, and triggering lung conditions such as emphysema and chronic bronchitis.
Source: Bio-Bio Technology