Early detection roadmap: organ screening → blood tests for many cancers
From mammograms and colonoscopies to a single blood draw that might screen for dozens of cancers, with the FDA's first decision imminent.
Screening has proven mortality benefit in five cancers. The MCED hypothesis is that cfDNA methylation can extend this to the cancers that kill most people without a screening test. 2026 is the year the evidence gets judged.
- 1943-2011historic
Organ-specific screening proven
Pap smear (1943), mammography (1970s-80s RCTs), colonoscopy/FIT, PSA (contested), low-dose CT for lung (NLST 2011). Each reduces mortality in its cancer; together they cover under half of cancer deaths.
- 2014-2021historic
cfDNA and methylation science
CCGA study (GRAIL) shows methylation classifiers detect >50 cancers with ~0.5% false positives and predict tissue of origin; Galleri launched as an LDT (2021); Cologuard and Epi proColon establish stool and blood DNA screening.
- 2021-2026current
Pivotal trials and first approvals
NHS-Galleri randomises 140,000; PATHFINDER 2 enrols 35,000; Shield becomes the first FDA-approved blood test for CRC screening (2024) and Medicare covers it; Exact launches Cancerguard as an LDT (2025); GRAIL files PMA (Jan 2026), advisory committee 23 Sep 2026. AI mammography reading validated at scale (MASAI).
- 2026-2030emerging
Decision and integration
FDA decision on Galleri; NHS decision on rollout; Medicare MCED coverage legislation; integration with risk-based screening (Mirai, polygenic scores); management pathways for positive signals with no imaging correlate; cost-effectiveness and overdiagnosis debates.
- 2030+speculative25%–50%likely
Speculative
Annual multi-analyte blood screening for adults over 50 with tissue-of-origin-directed imaging; MCED-detected pancreatic and ovarian cancers at resectable stages; risk-adapted intervals from AI; proteomic and fragmentomic layers improving stage I sensitivity.
Probability ranges are named estimates that the claim is borne out on roughly a five-year horizon. They are meant to be argued with: propose a revision with your name and reasoning via a pull request to src/data/confidence.ts.
Story
topOrgan-specific screening proven
Pap smear (1943), mammography (1970s-80s RCTs), colonoscopy/FIT, PSA (contested), low-dose CT for lung (NLST 2011). Each reduces mortality in its cancer; together they cover under half of cancer deaths.
Low-dose breast X-ray used for screening. Newer 3D versions find more cancers with fewer false alarms.
A CT scan is a fast 3D X-ray that shows the size and shape of tumours and whether they have spread.
cfDNA and methylation science
CCGA study (GRAIL) shows methylation classifiers detect >50 cancers with ~0.5% false positives and predict tissue of origin; Galleri launched as an LDT (2021); Cologuard and Epi proColon establish stool and blood DNA screening.
Pivotal trials and first approvals
NHS-Galleri randomises 140,000; PATHFINDER 2 enrols 35,000; Shield becomes the first FDA-approved blood test for CRC screening (2024) and Medicare covers it; Exact launches Cancerguard as an LDT (2025); GRAIL files PMA (Jan 2026), advisory committee 23 Sep 2026. AI mammography reading validated at scale (MASAI).
The largest cancer screening trial ever run, testing whether a multi-cancer blood test reduces late-stage diagnoses.
PATHFINDER 2 is the US real-world study of the Galleri test that forms the core of its FDA submission.
The first FDA-approved blood test for colorectal cancer screening (2024), now optionally reporting other cancers too.
A blood test screening for more than 50 cancers at once, before the FDA in September 2026.
Software that reads scans alongside radiologists, catching cancers earlier and predicting who is at risk.
Exact Sciences makes Cologuard and Oncotype DX and is launching Cancerguard MCED and Oncodetect MRD; it is being acquired by Abbott for $21B.
Decision and integration
FDA decision on Galleri; NHS decision on rollout; Medicare MCED coverage legislation; integration with risk-based screening (Mirai, polygenic scores); management pathways for positive signals with no imaging correlate; cost-effectiveness and overdiagnosis debates.
A single blood test intended to screen for dozens of cancers at once, including ones with no screening today.
Positive predictive value (PPV) is the chance that a test saying 'cancer' is right.
Stage shift means finding more cancers early and fewer late; it is the measurable goal of screening.
Speculative
Annual multi-analyte blood screening for adults over 50 with tissue-of-origin-directed imaging; MCED-detected pancreatic and ovarian cancers at resectable stages; risk-adapted intervals from AI; proteomic and fragmentomic layers improving stage I sensitivity.
Measuring the proteins in a tumour, which is what drugs actually hit, rather than the genes that encode them.
Whole-body MRI is an MRI of the entire body without radiation, used to find spread in myeloma and to screen people with high inherited cancer risk.