{"entity":{"id":"idea-prev-breath-voc-symptomatic-ruleout","kind":"idea","name":"A breath test to rule out cancer in people with vague symptoms","aka":[],"tldr":"Volatile compounds in breath differ in cancer. A breath test validated in truly symptomatic patients, not lab volunteers, could tell GPs who needs urgent scans and who can safely wait.","summary":"Breath VOC studies are mostly case-control and fail on replication. Propose validation exclusively in prospective symptomatic primary-care cohorts, targeting a rule-out use (negative predictive value above 99%) rather than diagnosis, with locked classifiers and external validation before any clinical use.","asOf":"2026-09-08","links":[{"label":"Bottleneck evidence (The hardest cancers are found late): Crosby et al., Early detection of cancer (Science 2022)","url":"https://doi.org/10.1126/science.aay9040"}],"tags":[],"related":[],"cancers":[],"sections":["early-detection","diagnostics"],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["ppv"],"trials":[],"people":[],"bottlenecks":["b-early-detection","b-biomarker-validation"],"keyPapers":["paper-crosby-science"],"journals":[],"dependsOn":[],"notes":[],"hypothesis":"A breath VOC panel achieves at least 99% NPV for any cancer within 12 months in symptomatic patients aged 50 and over, allowing safe deferral of imaging in at least 40% of referrals.","rationale":"The rule-out use case tolerates imperfect specificity and matches the actual clinical bottleneck, which is imaging capacity.","test":"5,000-patient prospective cohort through Rapid Diagnostic Centres with a pre-registered analysis plan.","maturity":"preclinical-evidence","actor":"research","cost":"medium","horizonYears":4},"route":"/ideas/idea-prev-breath-voc-symptomatic-ruleout/","neighbours":{"section":[{"id":"diagnostics","kind":"section","name":"Diagnostics & Biomarkers","route":"/fronts/diagnostics/"},{"id":"early-detection","kind":"section","name":"Early Detection & Screening","route":"/fronts/early-detection/"}],"term":[{"id":"ppv","kind":"term","name":"Positive predictive value (PPV)","route":"/terms/ppv/"}],"bottleneck":[{"id":"b-biomarker-validation","kind":"bottleneck","name":"Biomarkers are not validated or standardised","route":"/bottlenecks/b-biomarker-validation/"},{"id":"b-early-detection","kind":"bottleneck","name":"The hardest cancers are found late","route":"/bottlenecks/b-early-detection/"}],"paper":[{"id":"paper-crosby-science","kind":"paper","name":"Early detection of cancer","route":"/key-papers/paper-crosby-science/"}]}}