Overdiagnosis and false alarms

A positive blood test with no known tumour is frightening and hard to manage. A standard imaging cascade with a time limit, and a registry of what was found, would make these tests usable.

People are told a blood test can find fifty cancers, but not how many false alarms or how much is unknown. A short, tested decision aid before the test would make consent real.

Scans find unexpected lumps in the adrenal, thyroid, pancreas and lung. Nobody knows how many matter. A national cohort following them for ten years would tell us whom to watch.

Precancer is treated by cutting away part of the cervix, which raises pregnancy risks. A vaccine that makes the immune system clear the infected cells would avoid surgery.

Most people referred for blood in the urine do not have bladder cancer, yet all get cystoscopy. A urine DNA or methylation test could safely spare most of them.

Blood tests increasingly find precursor conditions like MGUS and smouldering myeloma, but most never progress. A registry with clear rules would stop early treatment outside trials.

Instead of separate screening programmes for a few cancers, assess every adult's overall cancer risk and offer blood tests, imaging and preventive treatment tuned to that risk, all inside one system that learns.

Papillary thyroid cancers under 1 cm almost never cause harm. Japanese hospitals have watched thousands safely. Make watching, not surgery, the default everywhere, with a registry.

Low-risk DCIS is a breast change that may never become cancer. Trials now show watching it is safe in the short term. The next step is a proper pathway and a name that does not say cancer.

Most lung nodules on CT are harmless but trigger years of follow-up scans. A validated AI score could discharge low-risk nodules immediately.

Whether a lesion is called precancer or cancer varies between pathologists, and over time the bar has drifted lower. AI reference reads could hold the line.

Some things called cancer, such as low-grade prostate lesions, almost never spread. An expert body could reclassify them, as cervical precancer was, so fewer people are overtreated.

For choices where the right answer depends on what the patient values (watching a slow prostate cancer, adjuvant chemo at 80, breast reconstruction), a tested decision aid becomes part of the consultation.

Hundreds of millions of CT scans are done each year for other reasons. Software could check each one for early lung, kidney, liver and pancreas changes, but only if a follow-up system exists.

Screening finds cancers that would never have caused harm, but programmes only report cancers found. Publishing the estimated overdiagnosis rate alongside would make the trade-off visible.

Frail women over 80 with small hormone-sensitive breast cancers may do as well with a daily tablet as with surgery. A trial would define who can safely avoid the operation.

Screening trials are judged on deaths, which take fifteen years to count, and on cancers found, which is the wrong direction. Preventing a man from turning up with cancer already in his bones happens three times as often as preventing a death, arrives years earlier, and is the outcome he cares about.

Melanoma diagnoses have soared while deaths barely changed, a sign of overdiagnosis. AI skin apps should be judged on whether dangerous thick melanomas fall, not how many spots they flag.

Trials show older women with the lowest-risk breast cancers gain almost nothing from radiotherapy after lumpectomy. Yet most still get it. Track and reward omission.

Autopsy studies decades ago found hidden prostate, thyroid and breast cancers in people who died of other causes, but they pre-date modern pathology. Repeating them with whole-body imaging and standardised histology would measure the reservoir of harmless cancer that every overdiagnosis estimate depends on.

Screening finds cancers that would never have caused harm alongside dangerous ones. Pair every screening test with a test that says which is which, so people with harmless findings can safely watch and wait.

PSA screening finds harmless prostate cancers that would never cause trouble. Selecting men by PSA plus a polygenic risk score, then MRI before any biopsy and targeted biopsy only for PI-RADS 4 to 5 lesions, finds the dangerous cancers and skips the rest; GOTEBORG-2 showed MRI-targeted biopsy halves overdiagnosis.

Low-risk patients often receive operations and radiotherapy they may not need, for example sentinel node biopsy in older women with favourable breast cancer or radiotherapy after breast-conserving surgery in genomically low-risk disease. Because no company will sponsor trials of leaving treatment out, health systems should fund them and keep the savings.

Bowel screening uses one blood-in-stool threshold for everyone. Setting it by age, sex and the person's previous results would find more cancers with the same number of colonoscopies.

Men on active surveillance for prostate cancer have repeat biopsies every year or two, a burden that drives some towards surgery. Triggering biopsy only when MRI, PSA density or new markers change, tested against scheduled biopsy in a 2,000-man non-inferiority trial, could be just as safe with far fewer biopsies.

Prostate MRI is good at telling you whether a man has a serious cancer and poor at telling you where all of it is. It missed at least one significant tumour in a third of men in the study that checked it against the whole removed prostate. Services that treat part of the gland, or follow men on imaging alone, are relying on the number they do not measure.

AI for screening should be judged on whether it finds dangerous cancers earlier and misses fewer, not just on whether it agrees with radiologists on old images.

In parts of Chile and northern India gallbladder cancer is common enough that a cheap ultrasound programme aimed at the highest-risk people might catch it while surgery can still cure it. Nobody has run the trial.

Instead of every woman every two or three years, an AI reading of the current mammogram would set who comes back in one year and who can safely wait four.

South Korea's thyroid cancer rate rose 15-fold after ultrasound screening, with no fall in deaths. A firm rule not to biopsy nodules under 1 cm, and not to screen, would prevent this harm elsewhere.

People with Barrett's oesophagus without dysplasia have endoscopies every few years, but the BOSS trial found no survival benefit. Redirecting effort to those with dysplasia would save harm and cost.

Screening someone unlikely to live ten years causes harm without benefit. A life-expectancy estimate in the medical record could stop invitations and prompt a conversation.

Small pancreatic cysts turn up on abdominal scans and are then followed for life. Low-risk cysts under 2 cm that are unchanged at five years rarely turn to cancer in Japanese and US cohorts, so a randomised trial of stopping surveillance would test whether years of scans can be spared.

Gleason 6 prostate lesions do not metastasise. A trial could show whether describing them without the word cancer leads more men to choose monitoring.

Most kidney tumours under 3 cm found by chance grow under 0.3 cm a year, rarely spread, and a fifth are benign. Surveillance with a biopsy for grade as the default in patients over 65, with a national registry and set triggers for surgery, could spare most of these operations.