# Positive predictive value (PPV)

Source: https://onco.cc/terms/ppv/  
OnCo record `ppv` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

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.

## Fields

- Kind: Term
- Last checked: 2026-09-04

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values
- Wikipedia: https://en.wikipedia.org/wiki/Positive_and_negative_predictive_values

## Connected records

- technologies: [Breath and volatile-organic-compound detection](https://onco.cc/technologies/breath-vocs/), [Multi-cancer early detection (MCED)](https://onco.cc/technologies/mced/), [Multitarget stool RNA test (ColoSense)](https://onco.cc/technologies/multitarget-stool-rna-test/), [Serum tumour markers: proper use and misuse](https://onco.cc/technologies/serum-tumour-markers/), [Urine tests for bladder cancer (cytology, FISH, RNA and methylation)](https://onco.cc/technologies/urine-bladder-cancer-tests/)
- cancers: [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/)
- ideas: [A 28-day national pathway for people with a positive multi-cancer blood test](https://onco.cc/ideas/idea-prev-mced-positive-resolution-pathway/), [A breath test to rule out cancer in people with vague symptoms](https://onco.cc/ideas/idea-prev-breath-voc-symptomatic-ruleout/), [A fund for prospective validation of academic biomarkers and companion diagnostics](https://onco.cc/ideas/idea-fund-biomarker-validation-fund/), [A urine DNA test to decide who with blood in the urine needs a camera test](https://onco.cc/ideas/idea-prev-urine-dna-haematuria-triage/), [A whole-population cancer interception programme: risk-stratify every adult, detect and intercept early](https://onco.cc/ideas/idea-moon-population-interception/), [Blood-based pancreatic cancer detection in new-onset diabetes](https://onco.cc/ideas/idea-mced-new-onset-diabetes/), [Every screening programme must publish its overdiagnosis rate each year](https://onco.cc/ideas/idea-prev-annual-overdiagnosis-reporting/), [Multi-cancer blood test as the first step for patients with non-specific symptoms](https://onco.cc/ideas/idea-prev-mced-non-specific-symptom-triage/), [Run the ENDPAC score on every new diabetes diagnosis after 50 and scan the high scorers](https://onco.cc/ideas/idea-pdac-new-onset-diabetes-risk-score-pathway/)
- terms: [CCGA: the Circulating Cell-free Genome Atlas behind the Galleri methylation test](https://onco.cc/terms/ccga-study/), [DETECT-A: a blood test plus PET-CT to screen 10,006 women with no symptoms](https://onco.cc/terms/detect-a-study/), [Lewis-negative (Lewis antigen-negative, CA 19-9 non-secretor) status](https://onco.cc/terms/lewis-negative/), [New-onset diabetes as a signal of pancreatic cancer (and the ENDPAC score)](https://onco.cc/terms/new-onset-diabetes-pancreatic-cancer/), [Screening](https://onco.cc/terms/screening/), [Sensitivity and specificity](https://onco.cc/terms/sensitivity-specificity/)
- key papers: [DETECT-A: a blood test plus PET-CT found treatable cancers in 10,000 women with no symptoms](https://onco.cc/key-papers/paper-detect-a-science-2020/), [Lead-Time Trajectory of CA19-9 as an Anchor Marker for Pancreatic Cancer Early Detection](https://onco.cc/key-papers/paper-fahrmann-ca19-9-lead-time-gastroenterology-2021/), [Model to Determine Risk of Pancreatic Cancer in Patients With New-Onset Diabetes](https://onco.cc/key-papers/paper-sharma-endpac-model-new-onset-diabetes-gastroenterology-2018/), [Multitarget stool DNA testing for colorectal-cancer screening](https://onco.cc/key-papers/paper-imperiale-multitarget-stool-dna-screening-nejm-2014/), [NELSON: volume-based CT screening reduces lung cancer deaths with fewer false alarms](https://onco.cc/key-papers/paper-nelson-nejm-2020/), [NHS-Galleri: design of the largest randomised trial of a multi-cancer blood test](https://onco.cc/key-papers/paper-nhs-galleri-design-cancers-2022/), [NLST: yearly low-dose CT scans cut lung cancer deaths in heavy smokers](https://onco.cc/key-papers/paper-nlst-nejm-2011/), [PATHFINDER: the first prospective test of a multi-cancer blood test in people without symptoms](https://onco.cc/key-papers/paper-pathfinder-lancet-2023/), [Performance of a multi-cancer early detection test in the randomized controlled NHS-Galleri trial](https://onco.cc/key-papers/paper-nhs-galleri-performance-nat-med-2026/), [Probability of pancreatic cancer following diabetes: a population-based study](https://onco.cc/key-papers/paper-chari-pancreatic-cancer-following-diabetes-gastroenterology-2005/)
- roadmaps: [ctDNA tests roadmap: from a curiosity in plasma to blood tests that decide treatment](https://onco.cc/roadmaps/ctdna-tests/), [Early detection roadmap: organ screening → blood tests for many cancers](https://onco.cc/roadmaps/early-detection-roadmap/), [Pancreatic cancer roadmap: from Whipple's operation to gemcitabine, FOLFIRINOX, adjuvant chemotherapy, PARP inhibition, KRAS inhibition, vaccines and the surveillance question](https://onco.cc/roadmaps/pancreatic-roadmap/)
- companies: [Harbinger Health](https://onco.cc/companies/harbinger-health/)
- trials: [NHS-Galleri](https://onco.cc/trials/nhs-galleri/), [PATHFINDER 2](https://onco.cc/trials/pathfinder-2/), [PSMA-PreRP](https://onco.cc/trials/psma-prerp/), [Vanguard Study (NCI Cancer Screening Research Network)](https://onco.cc/trials/vanguard-study/)
- bottlenecks: [Overdiagnosis and false alarms](https://onco.cc/bottlenecks/b-overdiagnosis/), [The hardest cancers are found late](https://onco.cc/bottlenecks/b-early-detection/)
- drugs: [Cancerguard](https://onco.cc/drugs/cancerguard/), [Cologuard](https://onco.cc/drugs/cologuard/)

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