Dual Methods Sharpen Cancer Diagnosis

Lung cancer may be more accurately diagnosed with combination of gene test and bronchoscopy

(RxWiki News) Lung lesions found through X-rays or CT scans may be a sign of cancer. While a bronchoscopy can give doctors a better picture, an additional gene test can help rule out cancer. Combining these tests appears to be a winning combination.

In a small clinical trial, researchers recently found that adding a gene test to a bronchoscopy may enable doctors to better distinguish patients with and without lung cancer.

"Quit smoking for the best way to prevent lung cancer."

Duncan Whitney, PhD, senior vice president of research and development at Allegro Diagnostics in Maynard, Mass., led the study of 330 patients—240 with lung cancer and 90 with benign lesions. Patients were either current or former smokers. All were undergoing bronchoscopy for suspicion of cancer.

If doctors find lung lesions in a scan, they often turn to bronchoscopy next to get a better diagnosis. For a bronchoscopy, a doctor passes a slender viewing instrument through the windpipe to look inside the airways of the lungs. Tiny brushes, needles or forceps can also be fed through this tube to collect very small tissue samples from the lungs.

Scientists in this study collected bronchial epithelial cells from the patients’ respiratory tracts. Epithelial cells line the organs. The cells were then analyzed with a gene expression test called the BronchoGen.

Gene expression signatures can help distinguish cancerous from non-cancerous cells. A gene expression signature is a unique pattern of genes that is related to a certain medical condition.

The gene expression test yielded a sensitivity of 77 percent. When combined with bronchoscopy, sensitivity improved to 94 percent. Sensitivity refers to the number of real lung cancer cases the test can identify.

The gene test also improved on findings of negative predictive value.

This number tells a patient how likely it is that he or she doesn’t have cancer if he or she tested positive for the disease. With bronchoscopy alone, this measure was 0.65, but add in the gene test and the value rose to 0.85. This is the percentage of people who have a negative test result who were properly diagnosed.

The number of false negatives was reduced by about 20 percent when using both gene test and bronchoscopy compared to bronchoscopy alone.

“The study confirmed the ability of a gene expression profile in normal airway epithelium [tissue] to distinguish patients with and without lung cancer,” concluded the authors.

Allegro sees its gene test as an addition to bronchoscopy that can help identify patients who test negative and spare them from more invasive procedures.

More extensive testing will be needed to better assess that value of this diagnostic method. The results of the study were presented in October at CHEST 2012: American College of Chest Physicians Annual Meeting and publish as an abstract in CHEST Journal. Allegro Diagnostics developed the test and funded the study.

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Review Date: 
November 12, 2012