What We Found Checking 1,358 Pages Against Their Sources
Cancer Explained is written with AI help. The risk is that a page says something its source does not. In October 2026 we went back through 1,358 pages, opened the sources each one cites, and recorded what held up and what did not. This page publishes the counts.
1,358
pages checked against their sources
10,935
specific claims recorded
76%
of pages (1,034) had at least one claim corrected, softened or removed
What happened to the 10,935 claims
| Outcome | Claims | Share | What it means |
|---|---|---|---|
| Matched the source | 7,270 | 66% | The claim was found in a source we opened, and the page kept it. |
| Softened or qualified | 1,692 | 15% | The page said more than the source did, so we narrowed or hedged the wording. |
| Removed | 929 | 8% | We could not find the claim, number or quote in a source we could open. |
| Corrected | 524 | 5% | The source said something different (a number, a date, a name), so we fixed the page. |
| Kept, could not be verified | 318 | 3% | General advice or standard wording that no opened source covered; kept and listed as unverified. |
| Other outcomes | 198 | 2% | Mixed or one-off outcomes that do not fit the rows above. |
| Contradicted by a source | 4 | 0% | A source we opened said the opposite; recorded for follow-up. |
How to read these numbers
Two in three claims matched their source. The rest tell us where AI-assisted writing drifts: it states things a little more strongly than a source does, adds a number or detail the source does not contain, or blends two sources together. Removing and softening were the most common fixes. Plain corrections were rarer.
A claim being “removed” does not mean it was wrong. It means we could not confirm it from a source we could open, so we took the conservative choice.
How we did it
- One record per page lists the sources opened, each claim checked, and what we did about it.
- Sources were federal and major-organization pages (for example NCI, CDC, FDA, NIH, MedlinePlus and the American Cancer Society), plus the original studies where a page cites them. Many publishers block automated reading, so a source we could not open is listed as unopened, not counted as a match.
- A script compares each changed page with its previous version and flags removed urgent-care wording, such as 911 and “call your care team” lines, and new links with no record.
- Every change is logged in our internal decision record, with the reason.
What the numbers cannot tell you
- This is not a medical review. No doctor or clinician reviewed these pages. We checked pages against sources, not against clinical practice.
- The counts cover the claims the checker listed on each page, not every sentence. The tally was made by grouping the first word of each outcome, so a few mixed outcomes sit under “Other.”
- The pass covered 1,358 pages out of more than 3,000 articles and 1,000 news stories. Earlier passes covered other pages. Some sources changed after we read them.
- We checked our own work, so this is a self-audit. An outside review has since found further issues, and we have been fixing them.
Cite this page
Cancer Explained. (2026, October 27). What We Found Checking 1,358 Pages Against Their Sources. https://cancerexplained.org/source-check-report/
To link to it, use the title above and the address https://cancerexplained.org/source-check-report/.
Questions or corrections: see corrections. The process behind every page is on our editorial process page.