Preventive health screening: what tests do you actually need at every age

Preventive health screening has long been a cornerstone of medicine, with the promise of catching disease while it is still treatable. But as medical technology has become more powerful — and more marketable — the line between helpful screening and unnecessary testing has blurred. After tech entrepreneur Bryan Johnson posted about his girlfriend's "vaginal microbiome report", Dr Pooja Lakshmin, writing in The Guardian, set out to redraw that line.

Lakshmin's framework is clear: a screening test, to be worth doing, must meet four criteria. The condition it targets must be common enough; early treatment must meaningfully improve the prognosis; the test must be accurate enough; and the harms — including the anxiety of false positives and the cascade of unnecessary follow-ups — must be smaller than the benefits.

Cardiovascular screening makes the cut for almost every adult. Over 40, blood pressure should be checked every two years and cholesterol every four or five; for smokers, diabetics or anyone with a family history of early heart disease, the frequency tightens. These tests are cheap, repeatable and tied to effective treatments — antihypertensives and statins among the best-studied drugs in modern medicine.

Colorectal — bowel — cancer screening should begin at 45. The NHS bowel-cancer programme sends a FIT (faecal immunochemical test) home kit to every adult between 50 and 74 every two years. For those with a family history or a known high-risk genetic syndrome, colonoscopy starts at 40, or 10 years before the youngest affected relative's diagnosis age.

For breast cancer, the NHS programme offers mammograms every three years to women aged 50 to 71; younger women at high risk — BRCA carriers or a dense family history — get MRI screening earlier. Cervical-cancer screening starts at 25; the new HPV-test-first protocol, rolled out in 2019-22, allows less frequent but more accurate screening cycles.

Prostate cancer is the major gap: the NHS does not screen asymptomatic men because the PSA test produces too many false positives and risks overtreatment. Men over 50 can request a PSA test from their GP under the informed-choice rules. For lung cancer, the United States recommends low-dose CT screening for heavy smokers aged 50 to 80; the UK is scaling its targeted lung-health-check pilots into a national rollout.

Skin-cancer dermoscopy, thyroid screening and full-body MRI scans — increasingly marketed as wellness — have weak evidence in average-risk adults. Whole-body MRI in particular finds incidentalomas in up to 30 per cent of scans, leading to biopsies and procedures most patients did not need. The US Preventive Services Task Force is unambiguous: whole-body MRI is not recommended in asymptomatic adults.

Genetic screening complicates the picture. Identifying BRCA1/BRCA2 mutations, Lynch syndrome or familial hypercholesterolaemia can be lifesaving when early intervention is available. But most direct-to-consumer genetic tests are educational only; clinical genetic decisions require an accredited laboratory and a genetic counsellor who can interpret what the variant means in context.

Immunisations are themselves a form of preventive screening. Annual influenza vaccine is recommended for adults over 50; tetanus boosters every 10 years; the shingles vaccine after 50; the HPV vaccine up to 26 (or later in specific groups); pneumococcal vaccine after 65. These items rarely appear on commercial screening menus but deliver more measurable benefit than most premium scans.

Lakshmin's summary is plain: "For every test, ask what it gains you and what it costs you before agreeing to it." As marketing accelerates, holding that line falls not only on the doctor but on the patient — an adult who walks in with the right questions is, in practice, the best defence against unnecessary testing.