medwireNews: A noninvasive single breath test has potential for the diagnosis of esophagogastric cancer, say researchers.
A previous study generated a diagnostic model comprising 12 volatile organic compounds (VOCs), analyzed from exhaled breath using selected ion flow tube mass spectrometry (SIFT-MS), from which they derived the 5-VOC model used in the current study.
A total of 163 patients with nonmetastatic esophagogastric adenocarcinoma and 172 individuals without cancer – just over half (51.7%) of whom had a normal upper gastrointestinal tract on endoscopy, while the remaining had benign conditions (most commonly esophagitis, gastritis, or duodenitis, in 34.3%) – were recruited from three UK hospitals for this validation study.
Participants were asked to perform a single nasal inhalation followed by complete exhalation through their mouth into 500 mL steel breath bags, which were fitted into the SIFT-MS instrument for analysis.
Receiver operating characteristic (ROC) curve analysis showed that the 5-VOC model could discriminate the presence versus absence of cancer with an accuracy of 0.85, which translated into a sensitivity of 80% and a specificity of 81% for diagnosing esophagogastric cancer.
This compared with corresponding values of 0.73, 59%, and 81% for a clinical parameters test derived from the UK’s NICE guidelines for endoscopy referral, say George Hanna (Imperial College London, UK) and co-authors.
They believe that the 5-VOC model could be useful in primary care, writing that “[i]f a clinician is presented with a patient with gastrointestinal symptoms that do not prompt referral based on NICE criteria, he/she would not need to watch and wait to see if symptoms worsen but could offer the exhaled breath test immediately.”
The study authors continue: “A positive result would warrant immediate referral for endoscopy. A negative test would permit the clinician to reassure the patient and offer retesting if symptoms persist.”
They do, however, admit that there is scope for improvement given the current sensitivity of 80%, by testing multiple breath samples perhaps.
Furthermore, as the majority (69.3%) of the cancer patients in the study had T3 or T4 disease, “the diagnostic accuracy of the test to identify early stage (T1) cancer remains undetermined,” the team writes in JAMA Oncology.
Hanna and colleagues conclude: “The next stage is a large-scale diagnostic accuracy study among the primary care population where the test is intended to be employed.”
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