References: how we check what we publish

Health information about cancer screening is full of confident claims, some of them selling something. This page sets out the rules the editors use to avoid adding to that pile, and then lists every source cited on the site so a reader can check the work.

Where facts come from

Every number, age, date, name and recommendation on the site comes from a page the editors opened and read in full, not from a search snippet or from memory. Preference goes to national health and research agencies, regulators, guideline bodies and peer-reviewed reviews, and the mix deliberately spans several countries. Commercial providers of tests or devices are not used as sources. A statement the editors could not trace to an opened source was left out rather than softened.

Dates and guideline changes

Screening recommendations are revised from time to time, and bodies in different countries revise on different schedules. Wherever a page states a recommendation it names the body and the date on the page the editors read, and the margin note says what that page said. The site was last checked on 11 October 2026. A reader who sees something different on a body's current website should trust that website and tell the editors.

When guidelines disagree

They often do. Bodies may weigh the same evidence differently, or serve different health systems, so one may recommend starting at 40 and another at 50. The pages set the positions side by side, say who made each, and avoid declaring a winner. Disagreement is not a sign that anyone is wrong; it is a sign that the decision involves trade-offs, which the benefits and harms page explains.

How uncertainty is worded

Words such as "may", "is associated with" and "in studies of" are used on purpose, and figures are attributed to the group of people they describe. Where authorities say the evidence is insufficient, as is the case for some questions about dense breasts, the pages say so instead of choosing a side.

What the pages do not do

The pages give no personal advice, no interpretation of anyone's results and no instruction to start, stop or skip screening. They do not rank clinics, tests or devices, and the guide carries no advertising. Anything a page says about what a body recommends is for groups of people; a doctor or screening service decides what fits an individual.

Corrections

If a page contains an error, a broken link or something out of date, tell the editors through the contact page. Confirmed errors are corrected on the page and the review date changes. The editors cannot answer personal medical questions.

Every source cited on this site

The list below is compiled automatically from the margin notes on all pages, grouped by publisher. Each source is followed by the pages that cite it.