TempoLife › Ominaisuudet › Health screening by age: which test and when › benefits-and-harms
What screening can and cannot do
Screening has real benefits and real harms, and the harms are the reason well-informed countries reach different answers from the same trials. Four ideas explain almost every disagreement.
This page describes screening programmes; it is not a diagnosis, not a personal risk assessment and not a substitute for your own health service. Age bands are set nationally and change — the invitation you receive, and the body named on your country page, outrank anything written here. Screening is for people without symptoms: a new lump, blood you can see, a mole that has changed, unexplained weight loss or a sudden change in vision or hearing needs a clinician now, whatever a recent screening result said.
False positives are not the same as overdiagnosis
These two get merged constantly and they are entirely different problems. A false positive is an alarm that turns out to be nothing: the mammogram that needed extra views, the stool test caused by a haemorrhoid, the HPV infection that clears. The cost is a period of fear and some extra tests, and then it is over. Overdiagnosis is far stranger: the finding is real, the pathology is genuine cancer under a microscope, and it would never have caused a symptom in that person’s lifetime. There is no way to tell at the time which of the diagnosed cancers those are, so everybody gets treated. That is why overdiagnosis converts directly into surgery, radiotherapy or hormone treatment that somebody did not need.
The trap in the survival statistics
Screening improves five-year survival even when it saves nobody, and this is the most consistently misused number in the whole field. If a cancer would have been found in 2032 and killed someone in 2035, finding it in 2028 turns a three-year survival into a seven-year one without changing the date of death by a day. That is lead-time bias. Length bias compounds it: slow-growing tumours spend longer in a detectable, symptomless state, so screening preferentially catches the indolent ones, which have a better outlook anyway. The only measure that is not vulnerable to either is mortality in a randomised comparison of invited versus not invited — which is why the trials that took decades were worth running.
Interval cases and the meaning of a clear result
Every programme has cancers that appear between two rounds and are diagnosed because of symptoms. They are counted, published, and used as a quality measure, and they are the reason a clear screening result must never silence a new symptom. A lump found four months after a normal mammogram, blood in the stool a year after a negative test, a mole that changed since the last look — none of these are contradicted by the earlier result. The screening test answered a question about a particular day.
Why sensible countries disagree
Put all of that together and the disagreements across this region stop looking like carelessness. Sweden invites women to mammography from 40 and Estonia from 50, because they weigh a smaller absolute benefit at younger ages against more false positives differently. Lithuania funds PSA testing and Sweden explicitly recommends against it, because they weigh a small mortality benefit against a large amount of overdiagnosis differently. Intervals lengthened when cervical screening moved to HPV testing because a better test justifies waiting longer, not because the service was cut. None of this is a country getting it wrong; it is a value judgement made in public, which is more than most medical decisions get.
What makes a good programme, on paper
The classic criteria have barely changed since Wilson and Jungner set them out for the World Health Organization in 1968, and they still explain the whole list on this site. The condition must be an important health problem with a recognisable early stage; there must be an accepted treatment that works better when started early; the test must be acceptable to the population and reasonably accurate; there must be capacity to investigate and treat everyone who screens positive; and the whole thing must be a continuing process rather than a one-off campaign. Glaucoma fails on none of these except the last, which is a good question to sit with.
Sources: Wilson and Jungner, Principles and practice of screening for disease, World Health Organization 1968 · Council Recommendation of 9 December 2022 on cancer screening (CELEX 32022H1213(01)) · checked 2026-09-07
Usein kysytyt kysymykset
What is overdiagnosis in screening?
Finding a real disease that would never have caused symptoms in that person’s lifetime. The pathology is genuine, which is why it cannot be distinguished from dangerous disease at the time, and why everyone found is treated.
Why is five-year survival a misleading measure of screening?
Because finding a cancer earlier lengthens survival even if the date of death is unchanged — that is lead-time bias. Screening also preferentially finds slow-growing tumours, which have a better outlook anyway. Only mortality in a randomised comparison avoids both problems.
Does a clear screening result mean I am safe until the next round?
No. Cancers that appear between rounds exist in every programme and are counted as a quality measure. A new symptom needs assessment on its own merits, whatever a recent test said.
Why do neighbouring countries have different screening ages?
Because they weigh the same evidence differently. Whether a smaller benefit at a younger age is worth more false alarms, and whether a small mortality gain is worth substantial overdiagnosis, are value judgements as much as scientific ones.
Where to go next
How screening invitations actually work
Every organised programme is a register, a rule and a letter. Knowing which of the three failed is usually enough to fix it — and in half the region there is no letter at all.
When the result is not normal
A positive screening test is a sorting decision, not a diagnosis. Knowing the shape of the pathway ahead of time removes most of the fear from the days of waiting.
The whole regional table
Every organised programme in the Nordic and Baltic countries, with the age band and interval for each.
Your own numbers, kept simply
TempoLife is a free tracker for weight, sleep, movement and blood pressure — the record between the letters, on your phone.