Biomarker discovery offers hope for lung cancer blood test

By Lauretta Ihonor, medwireNews Reporter

Blood levels of a variant form of the nuclear matrix protein Ciz1 are significantly higher in individuals with early- and late-stage lung cancer than in lung cancer-free individuals, researchers report.

When a threshold set at the mean of noncancer variant Ciz1 levels was used, the presence of the variant protein discriminated lung cancer patients from cancer-free individuals with an accuracy of 98%, irrespective of cancer stage.

Furthermore, the mean signal intensity of detected Ciz1 variant levels was significantly higher among individuals with lung cancer (n=119) than among those with no or nonmalignant lung disease (n=51), at respective intensities of 95.8 and 14.1.

This, say Dawn Coverley (University of York, UK) and colleagues, indicates that variant Ciz1 is highly specific for lung cancer and "holds considerable promise as the basis of a blood test for early-stage lung cancer."

When variant Ciz1 levels were measured among a second group of 160 individuals, the presence of the protein distinguished patients with stage 1 non-small-cell lung cancer (NSCLC; n=40) from age-matched smokers or individuals with benign lung nodules with an accuracy of 95%.

Among this patient group, variant Ciz1 measurement distinguished lung cancer patients from disease-free smokers, patients with benign lung nodules, and healthy controls, with respective specificities of 76%, 71%, and 74%.

The ability of the test to discriminate between malignant and benign nodules means that "we can pick out people who have small tumors in their lungs, without the need to take a biopsy or undergo surgery," said Coverley in a press statement.

She added: "We think that the test will be especially powerful when combined with X-ray or CT [computed tomography] imaging, and will offer doctors an alternative way to test whether an abnormal growth is cancerous.

"For the patient, this means that many could avoid invasive diagnostic procedures altogether."

Coverley and team measured blood levels of the variant protein using high-throughput Western Blot. However, they explain that Western Blot is not easy to conduct in a clinical setting.

The investigators therefore conclude that "although the data presented show that the biomarker holds considerable discriminatory power, the assay ultimately will need to switch platforms and be validated further in that context."

The research findings are published in the Proceedings of the National Academy of Sciences.

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