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Finding a cancer earlier means you know about it for longer, even if nothing you do changes the day you die. That extra stretch of knowing is called the lead time, and lead-time bias is the mistake of counting it as extra life. It is the single biggest reason survival figures make screening look better than it is.
Lead time is the interval between the moment a screening test finds a cancer and the moment that cancer would have been diagnosed because it caused symptoms. Lead-time bias is what happens when survival is measured from diagnosis: a man whose cancer is found five years earlier appears to survive five years longer even if the date of his death is unchanged. It is why survival from diagnosis is close to useless as a measure of whether a screening programme works, and why randomised screening trials report mortality in the whole invited population instead.
Prostate cancer has the longest lead time of any common cancer, and the honest figure is a range rather than a number. Draisma and Etzioni ran three independently built models of prostate cancer progression and detection, all calibrated to Surveillance, Epidemiology, and End Results incidence in United States men aged 54 to 80 between 1985 and 2000. Among screen-detected cancers that would have surfaced in the man's lifetime, mean lead time was 5.4 to 6.9 years across the three models; the original MISCAN model fitted instead to the Rotterdam section of the European screening trial gave 7.9 years. Published estimates before that work spanned 3 to 12 years. The three models agreed closely with each other for any single definition of lead time and disagreed substantially across definitions, which is the paper's real finding: the number is a property of the question, not of the disease.
The consequence is practical. Lead time is what generates overdiagnosis: if the lead time is longer than the man's remaining life, the cancer would never have troubled him, and the same modelling put overdiagnosis at 23 to 42 percent of screen-detected cancers in the United States calibration and 66 percent in the Rotterdam one. It is also why the 2018 United States task force statement expresses benefit as deaths and metastatic cases prevented per 1,000 men screened over about 13 years rather than as a survival rate, and why the two 2009 randomised trials, ERSPC and PLCO, are the evidence rather than any registry series.
The honest state of the overdiagnosis question. Prostate cancer is common in the prostates of men who die of something else, screening finds a proportion of it, and how much of that is harm depends on what is done next. The fix is not a better estimate but fewer treatments for the cancers that do not need them.
The clearest case in cancer screening of a national body acting on the harms rather than the headline. Whether it was right is still argued: testing and localised-stage diagnosis fell, and the long-term effect on metastatic presentation and mortality is the subject of the studies that followed.
The evidence that prostate-specific antigen screening works, stated together with the price. It is the reason screening programmes are debated rather than simply adopted, and the reason every subsequent proposal, from magnetic resonance imaging first to risk-model invitation, is judged on whether it keeps the mortality benefit while reducing the 48.
The reference for anyone quoting an overdiagnosis figure in prostate cancer. The honest statement is a range with its definition and its population attached, and the paper is the reason this page does not print one number.
The trial that made prostate screening contested in the United States, and the reason the 2012 task force recommended against it. Its main lesson is methodological: a screening trial whose control group screens itself cannot measure the effect of screening.
The number that anchors the overdiagnosis argument in prostate cancer: over a million American men treated for a cancer that, for most of them, was never going to surface. It is the reason active surveillance exists as a formal pathway and the reason magnetic resonance imaging was brought in front of the biopsy.
The paper that made opportunistic prostate-specific antigen testing routine, and the source of the threshold still printed on laboratory reports. Everything in the overdiagnosis literature is, in effect, an audit of what this recommendation did when it was applied to whole populations.
Shares PSA and MRI-first prostate cancer screening, Overdiagnosis, PSA (prostate-specific antigen), Localised prostate cancer, intermediate risk and the tags gu, prostate-glossary.
Shares PSA and MRI-first prostate cancer screening, PSA (prostate-specific antigen), Localised prostate cancer, intermediate risk, Localised prostate cancer, very low and low risk and the tags gu, prostate-glossary.
Shares Overtreatment, Localised prostate cancer, intermediate risk, Localised prostate cancer, very low and low risk, Screening and the tags gu, prostate-glossary.
Shares Judge a prostate screening programme on metastatic presentation, not on incidence or mortality, The hardest cancers are found late, Trial design, endpoints and cost, Prostate cancer and the tags gu, prostate-glossary.
Shares Localised prostate cancer, intermediate risk, Localised prostate cancer, very low and low risk, Prostate cancer and the tags gu, prostate-glossary.
Shares PSA (prostate-specific antigen), Trial design, endpoints and cost, Prostate cancer and the tags gu, prostate-glossary.
Shares PSA (prostate-specific antigen), Trial design, endpoints and cost, Prostate cancer and the tags gu, prostate-glossary.
Shares PSA (prostate-specific antigen), Prostate cancer and the tags gu, prostate-glossary.