{"entity":{"id":"ppv","kind":"term","name":"Positive predictive value (PPV)","aka":[],"tldr":"Positive predictive value (PPV) is the chance that a positive test result is actually right: true positives divided by all positives. Because it falls as a disease becomes rarer, even a specific screening test gives mostly false alarms when prevalence is low, which is why PPV decides whether a multi-cancer blood test is useful.","summary":"Positive predictive value (PPV) is the probability that a test result saying 'cancer' is actually correct. It is true positives divided by all positives, so it depends heavily on how common the disease is in the tested population: even a highly specific screening test yields many false alarms when prevalence is low. This makes PPV central to judging Multi-cancer early detection (MCED) tests such as Galleri, and it recurs in the PATHFINDER 2 trial, the early detection roadmap, and the bottlenecks on cancers found late and on overdiagnosis and false alarms. It is also cited by Breath and volatile-organic-compound detection, Harbinger Health, and ideas on a national pathway for people with a positive multi-cancer blood test and urine DNA triage for haematuria.","asOf":"2026-09-04","wikipedia":"https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values"}],"tags":[],"related":[],"cancers":[],"sections":[],"technologies":["mced"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Diagnostics & imaging"},"route":"/terms/ppv/","neighbours":{"technology":[{"id":"breath-vocs","kind":"technology","name":"Breath and volatile-organic-compound detection","route":"/technologies/breath-vocs/"},{"id":"mced","kind":"technology","name":"Multi-cancer early detection (MCED)","route":"/technologies/mced/"},{"id":"multitarget-stool-rna-test","kind":"technology","name":"Multitarget stool RNA test (ColoSense)","route":"/technologies/multitarget-stool-rna-test/"},{"id":"serum-tumour-markers","kind":"technology","name":"Serum tumour markers: proper use and misuse","route":"/technologies/serum-tumour-markers/"},{"id":"urine-bladder-cancer-tests","kind":"technology","name":"Urine tests for bladder cancer (cytology, FISH, RNA and methylation)","route":"/technologies/urine-bladder-cancer-tests/"}],"cancer":[{"id":"pancreatic","kind":"cancer","name":"Pancreatic ductal adenocarcinoma","route":"/cancers/pancreatic/"}],"idea":[{"id":"idea-prev-mced-positive-resolution-pathway","kind":"idea","name":"A 28-day national pathway for people with a positive multi-cancer blood test","route":"/ideas/idea-prev-mced-positive-resolution-pathway/"},{"id":"idea-prev-breath-voc-symptomatic-ruleout","kind":"idea","name":"A breath test to rule out cancer in people with vague symptoms","route":"/ideas/idea-prev-breath-voc-symptomatic-ruleout/"},{"id":"idea-fund-biomarker-validation-fund","kind":"idea","name":"A fund for prospective validation of academic biomarkers and companion diagnostics","route":"/ideas/idea-fund-biomarker-validation-fund/"},{"id":"idea-prev-urine-dna-haematuria-triage","kind":"idea","name":"A urine DNA test to decide who with blood in the urine needs a camera test","route":"/ideas/idea-prev-urine-dna-haematuria-triage/"},{"id":"idea-moon-population-interception","kind":"idea","name":"A whole-population cancer interception programme: risk-stratify every adult, detect and intercept early","route":"/ideas/idea-moon-population-interception/"},{"id":"idea-mced-new-onset-diabetes","kind":"idea","name":"Blood-based pancreatic cancer detection in new-onset diabetes","route":"/ideas/idea-mced-new-onset-diabetes/"},{"id":"idea-prev-annual-overdiagnosis-reporting","kind":"idea","name":"Every screening programme must publish its overdiagnosis rate each year","route":"/ideas/idea-prev-annual-overdiagnosis-reporting/"},{"id":"idea-prev-mced-non-specific-symptom-triage","kind":"idea","name":"Multi-cancer blood test as the first step for patients with non-specific symptoms","route":"/ideas/idea-prev-mced-non-specific-symptom-triage/"},{"id":"idea-pdac-new-onset-diabetes-risk-score-pathway","kind":"idea","name":"Run the ENDPAC score on every new diabetes diagnosis after 50 and scan the high scorers","route":"/ideas/idea-pdac-new-onset-diabetes-risk-score-pathway/"}],"term":[{"id":"ccga-study","kind":"term","name":"CCGA: the Circulating Cell-free Genome Atlas behind the Galleri methylation test","route":"/terms/ccga-study/"},{"id":"detect-a-study","kind":"term","name":"DETECT-A: a blood test plus PET-CT to screen 10,006 women with no symptoms","route":"/terms/detect-a-study/"},{"id":"lewis-negative","kind":"term","name":"Lewis-negative (Lewis antigen-negative, CA 19-9 non-secretor) status","route":"/terms/lewis-negative/"},{"id":"new-onset-diabetes-pancreatic-cancer","kind":"term","name":"New-onset diabetes as a signal of pancreatic cancer (and the ENDPAC score)","route":"/terms/new-onset-diabetes-pancreatic-cancer/"},{"id":"screening","kind":"term","name":"Screening","route":"/terms/screening/"},{"id":"sensitivity-specificity","kind":"term","name":"Sensitivity and specificity","route":"/terms/sensitivity-specificity/"}],"paper":[{"id":"paper-detect-a-science-2020","kind":"paper","name":"DETECT-A: a blood test plus PET-CT found treatable cancers in 10,000 women with no symptoms","route":"/key-papers/paper-detect-a-science-2020/"},{"id":"paper-fahrmann-ca19-9-lead-time-gastroenterology-2021","kind":"paper","name":"Lead-Time Trajectory of CA19-9 as an Anchor Marker for Pancreatic Cancer Early Detection","route":"/key-papers/paper-fahrmann-ca19-9-lead-time-gastroenterology-2021/"},{"id":"paper-sharma-endpac-model-new-onset-diabetes-gastroenterology-2018","kind":"paper","name":"Model to Determine Risk of Pancreatic Cancer in Patients With New-Onset Diabetes","route":"/key-papers/paper-sharma-endpac-model-new-onset-diabetes-gastroenterology-2018/"},{"id":"paper-imperiale-multitarget-stool-dna-screening-nejm-2014","kind":"paper","name":"Multitarget stool DNA testing for colorectal-cancer screening","route":"/key-papers/paper-imperiale-multitarget-stool-dna-screening-nejm-2014/"},{"id":"paper-nelson-nejm-2020","kind":"paper","name":"NELSON: volume-based CT screening reduces lung cancer deaths with fewer false alarms","route":"/key-papers/paper-nelson-nejm-2020/"},{"id":"paper-nhs-galleri-design-cancers-2022","kind":"paper","name":"NHS-Galleri: design of the largest randomised trial of a multi-cancer blood test","route":"/key-papers/paper-nhs-galleri-design-cancers-2022/"},{"id":"paper-nlst-nejm-2011","kind":"paper","name":"NLST: yearly low-dose CT scans cut lung cancer deaths in heavy smokers","route":"/key-papers/paper-nlst-nejm-2011/"},{"id":"paper-pathfinder-lancet-2023","kind":"paper","name":"PATHFINDER: the first prospective test of a multi-cancer blood test in people without symptoms","route":"/key-papers/paper-pathfinder-lancet-2023/"},{"id":"paper-nhs-galleri-performance-nat-med-2026","kind":"paper","name":"Performance of a multi-cancer early detection test in the randomized controlled NHS-Galleri trial","route":"/key-papers/paper-nhs-galleri-performance-nat-med-2026/"},{"id":"paper-chari-pancreatic-cancer-following-diabetes-gastroenterology-2005","kind":"paper","name":"Probability of pancreatic cancer following diabetes: a population-based study","route":"/key-papers/paper-chari-pancreatic-cancer-following-diabetes-gastroenterology-2005/"}],"roadmap":[{"id":"ctdna-tests","kind":"roadmap","name":"ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment","route":"/roadmaps/ctdna-tests/"},{"id":"early-detection-roadmap","kind":"roadmap","name":"Early detection roadmap: organ screening → blood tests for many cancers","route":"/roadmaps/early-detection-roadmap/"},{"id":"pancreatic-roadmap","kind":"roadmap","name":"Pancreatic cancer roadmap: from Whipple's operation to gemcitabine, FOLFIRINOX, adjuvant chemotherapy, PARP inhibition, KRAS inhibition, vaccines and the surveillance question","route":"/roadmaps/pancreatic-roadmap/"}],"company":[{"id":"harbinger-health","kind":"company","name":"Harbinger Health","route":"/companies/harbinger-health/"}],"trial":[{"id":"nhs-galleri","kind":"trial","name":"NHS-Galleri","route":"/trials/nhs-galleri/"},{"id":"pathfinder-2","kind":"trial","name":"PATHFINDER 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