Markar SR, et al. - Experts ascertained the accuracy of a breath test for the diagnosis of esophagogastric cancer (OGC) in a multicenter validation study. In noninvasive diagnosis of OGC, the potential of breath analysis in the clinical setting was demonstrated in the findings. Among the intended population in primary care where the test will be applied, the next step was to establish the diagnostic accuracy of the test.

Methods

• Authors conducted the patient recruitment for this diagnostic validation study at 3 London hospital sites, with breath samples returned to a central laboratory for selected ion flow tube mass spectrometry (SIFT-MS) analysis.
• The sample size required was 325 patients, based on a 1:1 cancer:control ratio, and maintaining a sensitivity and specificity of 80%.
• All cancer patients on a curative treatment pathway were recruited consecutively.
• A total of 172 of the 335 patients included were in the control group and 163 had OGC.
• Using secure 500-mL steel breath bags, breath samples were collected and analyzed by SIFT-MS.
• Sampling room air, training all researchers in breath sampling, regular instrument calibration, and unambiguous volatile organic compounds (VOCs) identification by gas chromatography mass spectrometry were the quality assurance measures.
• They identified the risk of cancer based on a previously generated 5-VOCs model and compared with histopathology-proven diagnosis.

Results

• Results suggested that the patients in the OGC group were older (median [IQR] age 68 [60-75] vs 55 [41-69] years) and had a greater proportion of men (134 [82.2%]) than women (81 [47.4%]) compared with the control group.
• As per the findings, 123 (69%) among the 163 patients with OGC, had tumor stage T3/4, and 106 (65%) had nodal metastasis on clinical staging.
• Data demonstrated that to generate a receiver operator characteristic curve, with good diagnostic accuracy, area under the curve of 0.85 the predictive probabilities generated by this 5-VOCs diagnostic model were used.
• Researchers found that for the diagnosis of OGC, this translated to a sensitivity of 80% and specificity of 81%.