Which screening tests are actually worth having

The instinct that more testing must be better is one of the most expensive intuitions in healthcare, and it is wrong often enough to be worth examining.

What a screening programme has to demonstrate

National programmes are assessed against criteria that have been broadly stable since the 1960s.

The condition must be an important health problem with a recognisable early stage.

There must be a treatment that works better when started early — which is the criterion that eliminates most candidates.

The test must be accurate, acceptable and safe.

The programme must have evidence from randomised trials that it reduces mortality or serious morbidity.

And the benefits must outweigh the harms, including anxiety, false positives, unnecessary investigation and overdiagnosis.

Very few tests clear all of these, which is why the list of established programmes is short.

The ones with the strongest case

Broadly consistent across countries, with differences in age and interval.

Cervical screening, which has moved to primary testing for high-risk HPV in many programmes, is more sensitive than cytology alone and permits longer intervals.

Bowel cancer screening, usually with a faecal immunochemical test posted to the home, with colonoscopy for positive results.

Uptake is the weak point rather than the evidence.

Breast screening by mammography, where mortality benefit is established and where overdiagnosis is a genuine and quantified harm — informed choice material now states both.

Abdominal aortic aneurysm screening for men at a specified age in several countries, a single ultrasound with a good evidence base.

Diabetic eye screening for anyone with diabetes, which prevents avoidable blindness and is one of the highest-value checks available.

Antenatal and newborn screening programmes, which detect conditions where early treatment changes outcomes entirely.

The contested ones

Where reasonable people disagree.

Prostate specific antigen testing, which detects cancers that would never have caused harm alongside those that would, and where the trade-off between mortality benefit and overdiagnosis is genuinely finely balanced.

Most countries have shared decision-making rather than a programme.

Lung cancer screening with low-dose CT in high-risk smokers and former smokers, where trial evidence is now good and programmes are being introduced in several countries.

Ovarian cancer screening, where large trials have not shown a mortality benefit.

And whole-body imaging, which has no evidence of benefit in asymptomatic people and a well-documented rate of incidental findings.

Overdiagnosis, explained plainly

The concept that makes sense of all of this.

Overdiagnosis is the detection of a condition that would never have caused symptoms or death within the person's lifetime.

It is not a mistake or a false positive — the disease is genuinely there.

The harm is that the person is treated for something that was never going to hurt them, with all the cost, risk and anxiety that treatment involves.

Thyroid cancer is the clearest documented example, where diagnosis rates have risen dramatically in some countries with imaging while mortality has not changed.

What it costs

The practical arithmetic.

National programme screening is generally free at the point of use where it exists, funded because it demonstrably saves money and lives.

Private health checks and executive screening packages cost anywhere from modest to substantial sums annually, and typically bundle tests that no programme recommends.

The follow-up costs of an incidental finding are the part nobody prices: repeat imaging, specialist referral, sometimes biopsy — with the financial and physical cost falling on you or on a system that had not budgeted for it.

Which means the honest comparison is not the price of the check but the expected cost of everything it sets in motion.

What to do instead of buying a package

The highest-value actions.

Attend every programme you are invited to, which is free and which a substantial minority of people decline.

Have your blood pressure measured, which is the single most valuable measurement in preventive medicine and costs almost nothing.

Have a cardiovascular risk assessment at the age recommended locally.

Be tested for diabetes if you have risk factors.

Attend diabetic eye and foot screening if relevant.

Get vaccinated according to the adult schedule.

And see someone about symptoms rather than testing broadly in their absence, since a symptom is far more informative than any untargeted panel.

General information only, not medical advice. Screening programmes vary by country — consult a qualified clinician about which tests apply to you.