How to choose the best early disease screening?
To choose screening tests well, ask five questions in order: how likely am I to have this disease; has this test been shown to help people like me live longer or better; what happens if it comes back positive; what are the harms of a false alarm or of finding something that would never have mattered; and what would I actually do with the result. Most heavily marketed tests fail the second question. What is left is a short, personal list: blood pressure and cholesterol markers for nearly everyone, guideline cancer screens by age, lung CT for heavy smokers, heart scans for those at intermediate risk, and genetic tests for a strong family history.
Choose early disease screening by asking five questions in order, ranked here by how many tests each one eliminates: What is my actual risk for this disease — age, sex, family history, smoking, existing conditions — because screening's value scales with risk and most marketed tests are offered to people at low risk; Does this test have randomised or strong cohort evidence that acting on its result improves an outcome in people like me — which removes multi-cancer blood tests, whole-body MRI, polygenic scores and genome sequencing at once; What happens after a positive — the confirmatory test, its risk, and who manages it; What are the quantified harms — false positives, overdiagnosis, and the cascade they trigger; and What would I do differently with the result — if nothing, the test is information without a decision. Run in order, the method leaves a short list that depends on the person: blood pressure and ApoB with lipoprotein(a) for almost everyone; guideline cancer screening — colorectal, breast, cervical — by age; low-dose CT for heavy smokers; coronary calcium scoring for intermediate cardiovascular risk; targeted genetic testing for a strong family history. It leaves out, for most people, everything sold as 'comprehensive'.
- Risk comes first because screening a low-risk person turns a good test into a false-positive generator.
- Outcome evidence is the question that removes most of the market, and it can be checked: a randomised trial with a mortality or morbidity endpoint either exists or does not.
- A screen is only as good as what follows a positive; a test with no defined confirmatory pathway is a source of anxiety, not a screen.
- Harms are quantified for the good tests and unquantified for the marketed ones — which is not the same as absent.
- If the result would not change a decision, the test has no value regardless of accuracy.
The five questions, ranked by what they eliminate
Ranked on: how many marketed screening tests each question removes when asked in order, and how often skipping it is the route to a harmful or useless test. The order is the order to ask.
| # | Option | Verdict | Grade |
|---|---|---|---|
| 1 | 1. What is my actual risk for this disease? | Turns the right test into the wrong one, or back | GRADE AEstablished |
| 2 | 2. Has acting on this test's result been shown to improve an outcome in people like me? | Removes most of the market in one question | GRADE AEstablished |
| 3 | 3. What happens after a positive? | A screen without a pathway is anxiety with a price | GRADE AEstablished |
| 4 | 4. What are the quantified harms? | False positives, overdiagnosis, and the cascade | GRADE BPromising |
| 5 | 5. What would I do differently with the result? | If nothing, the test has no value | GRADE BPromising |
- 01
1. What is my actual risk for this disease?
GRADE AEstablishedTurns the right test into the wrong one, or backAge, sex, family history, smoking, weight, existing conditions and, for a few diseases, a single genetic marker. A test's positive predictive value depends on how common the disease is in the person tested; low-dose CT is life-saving in heavy smokers and a false-positive machine in never-smokers. Every marketed 'comprehensive' screen is offered without this question, which is why it fails the next one.
- 02
2. Has acting on this test's result been shown to improve an outcome in people like me?
GRADE AEstablishedRemoves most of the market in one questionA randomised trial — or, for a few tests, strong cohort evidence — with a mortality or morbidity endpoint either exists or it does not. It exists for colorectal, breast and cervical screening, low-dose CT in smokers, blood pressure, and ApoB through its treatment. It does not exist for multi-cancer blood tests (the one trial missed), whole-body MRI, polygenic scores, whole-genome sequencing in the well, or most 'longevity panels'.
- 03
3. What happens after a positive?
GRADE AEstablishedA screen without a pathway is anxiety with a priceThe confirmatory test, its accuracy and risk, who orders and manages it, and who pays. A positive Galleri result took a median 162 days to resolve; a whole-body MRI finding often has no guideline for follow-up at all. A good screen has a defined next step; a marketed one has a phone number.
- 04
4. What are the quantified harms?
GRADE BPromisingFalse positives, overdiagnosis, and the cascadeFor the good tests the harms are measured: false-positive rates, overdiagnosis (around half of screen-detected lung cancers in the best trials), biopsy and procedure risks. For the marketed tests the harms are unmeasured, which is not the same as absent — a third of whole-body MRIs generate a finding and most physicians report cascades with no benefit.
- 05
5. What would I do differently with the result?
GRADE BPromisingIf nothing, the test has no valueA positive should lead to a treatment or a decision with evidence behind it. Knowing a polygenic score, a biological age or a p-tau217 result in the absence of symptoms leads, for most people, to nothing that was not already advisable. Information that changes no decision is not screening; it is a subscription.
What survives the five questions, for whom
A screening list by risk profile
| Profile | Screens that pass all five questions | Screens that fail — and why |
|---|---|---|
| Adult, average risk, any age | Blood pressure; ApoB and lipoprotein(a) once; guideline cervical, colorectal and breast screening by age and sex | Multi-cancer blood test (no outcome evidence); whole-body MRI (no evidence, harms); polygenic scores (no decision changes) |
| Heavy smoker or recent ex-smoker, 50+ | Everything above plus annual low-dose CT | Same as above; a multi-cancer blood test does not replace CT |
| Intermediate cardiovascular risk | Everything above plus a coronary artery calcium score to guide statin decisions | CT coronary angiography without symptoms; carotid ultrasound as a routine screen |
| Strong family history of a specific cancer | Targeted genetic testing for the relevant gene; earlier or more frequent guideline screening as indicated | Whole-genome sequencing (mostly variants of uncertain significance); polygenic scores |
| Cognitive symptoms | Clinical assessment; p-tau217 or PET as directed by a specialist | p-tau217 ordered while cognitively normal (no treatment changes the course enough to justify it) |
| Worried and well | The average-risk list, and a conversation about why the rest is not on it | Every 'comprehensive' package |
Frequently asked questions
How do I choose the best early disease screening?
Ask five questions in order: what is my actual risk for this disease; has acting on this test been shown to improve an outcome in people like me; what happens after a positive; what are the quantified harms of false positives and overdiagnosis; and what would I do differently with the result. Most marketed tests fail the second. What survives is a short personal list — blood pressure and ApoB for nearly everyone, guideline cancer screens by age, low-dose CT for heavy smokers, calcium scoring for intermediate cardiovascular risk, targeted genetic testing for a strong family history.
Why does my risk level matter so much for screening?
Because a test's chance of being right when positive depends on how common the disease is in the person tested. The same low-dose CT that saves lives in heavy smokers mostly generates false positives in never-smokers. Marketed 'comprehensive' screens are offered without assessing risk, which is why they produce findings rather than benefits.
Which screening tests have outcome evidence?
Colorectal, breast and cervical cancer screening within guidelines; low-dose CT in heavy smokers; blood-pressure measurement and ApoB through the treatments they lead to; and coronary calcium scoring as a guide to statin decisions in intermediate-risk adults. Multi-cancer blood tests, whole-body MRI, polygenic scores and whole-genome sequencing in healthy adults do not — and the one randomised trial of a multi-cancer test missed its endpoint.
What should I ask about what happens after a positive result?
What the confirmatory test is, how accurate and risky it is, who orders and manages it, how long it takes and who pays. A positive multi-cancer blood test took a median 162 days to resolve in one study; a whole-body MRI finding often has no follow-up guideline. A good screen has a defined next step; without one, a positive is anxiety with a price.
Is a comprehensive screening package a good way to cover everything?
No. Bundling screens multiplies false positives rather than adding benefits; the largest review of general health checks — 17 trials, 251,891 people — found no effect on mortality, and expensive executive packages have been documented including tests recommended against while omitting recommended ones. Screening is a set of individual decisions, and a package is those decisions made by nobody.
Should I get a genetic test for early disease detection?
Targeted testing for a specific gene makes sense with a strong family history of a particular cancer or condition, because the result changes screening and sometimes treatment. Polygenic risk scores shift risk modestly and rarely change a decision; whole-genome sequencing in a healthy adult mostly yields variants of uncertain significance. The family history, not the technology, decides.
Keep reading
- Early disease detection
The full evidence ledger the five questions draw on.
- What is the most accurate early disease detection method?
Accuracy, disease by disease.
- How to choose the best longevity clinic package?
The same method applied to the bundles clinics sell.
- Which blood tests are best for tracking longevity?
The cardiovascular markers that pass all five questions.
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