Lung cancer

Breath test better than low dose CT for lung cancer screening

A simple breath test that detects volatile organic compound (VOC) biomarkers may be the way forward for lung cancer screening, according to Chinese researchers.

In an evaluation study, exhaled breath analysis was found to be a practical and reliable test for identifying patients with lung cancer, potentially offering greater accuracy and convenience over current models such as low dose CT screening in high risk individuals.

Published in JAMA Network Open, the case-control diagnostic study involved 139 patients with lung cancer and 289 healthy adult controls who provided a breath sample for analysis with high-pressure photon ionisation time-of-flight mass spectrometry (HPPI-TOFMS).

The analysis, which took only 60 seconds, showed that breath test had a sensitivity of 92.97% (CI 4.64%) for detecting lung cancer and a specificity of 96.68% (CI 2.21%) in the initial detection evaluation, providing an accuracy of  95.51% (CI 1.93%) for accuracy.

When subject to validation in 47 participants), the breath analysis model showed a sensitivity of 100%, a specificity of 92.86%, an accuracy of 95.74%, and an AUC of 0.9586.

The breath tests were conducted in patients newly diagnosed with lung cancer who had been referred to a tertiary hospitals for thoracic surgery or endobronchial ultrasonography-guided transbronchial needle aspiration (EBUS-TBNA).

Of the 120 patients in an initial ‘discovery’ cohort, 86% had adenocarcinoma, 12% had squamous cell carcinoma and 1% had small cell lung cancer. Most of the patients had early stage lung cancer (81% TNM stage I and 10% stage II).

The study investigators said the (HPPI-TOFMS) method was simple and convenient to use, in contrast to other techniques such as gas-chromatography mass spectrometry (GC-MS)  that had impractical pretreatment steps, a time consuming detection process and poor tolerance for humidified breath samples.

They said the new method was feasible in clinical practice and they had developed standard protocols – such as use of CO2 detection to ensure alveolar lung sample analysis – to ensure more consistent and reliable results.

“HPPI is one of the most powerful and popular soft ionisation techniques for online monitoring of trace VOCs, because of its high ionisation efficiency, high molecular ion yield, and low degree of fragmentation. These features make HPPI-TOFMS hold potentially great value for clinical application,” they wrote.

With high sensitivity and specificity, breath testing could offer advantages over the current low-dose CT lung screening models which had drawbacks of radiation exposure, high cost, and a high false-positive rate and over-investigation, they said.

“This diagnostic study’s results suggest encouraging findings that breath testing may be a reliable approach to lung cancer detection and HPPI-TOFMS may provide fast and precise detection of exhaled breath,” they concluded.

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