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Cancer Atlas 2026 · Colorectal cancer

Colorectal Cancer Biomarkers and Early Detection in 2026: Screening, CEA and ctDNA

Colorectal cancer is the third most diagnosed cancer in the world and the second leading cause of cancer death. This article covers the burden, how stage shapes survival, the screening tests recommended as of 1 October 2026, and what CEA and circulating tumor DNA can and cannot do.

By OncoFirm™ Scientific TeamPublished 1 Oct 2026Updated 1 Oct 2026Sources peer-reviewed, guidelines, regulators, linked

At a glance

Global burden

About 2.04 million new cases and 918,000 deaths in 2024 (GLOBOCAN 2024).

United States, 2026

About 158,850 new cases and 55,230 deaths. Rising about 3% a year in ages 20 to 49.

Screening

From age 45 in the US. Stool tests and colonoscopy are preferred; approved blood tests are a fallback.

Key biomarkers

CEA in blood for monitoring. RAS, BRAF V600E, MMR/MSI and HER2 in tissue for treatment choice.

OncoFirm™ status

CEA assay in development, research use only. Not cleared or approved, not for sale, not a screening test.

On this page

Key numbers

Colorectal cancer in three numbers

2.04 Mnew colorectal cancer cases worldwide in 2024
91.3%5-year relative survival when found at localized stage (US)
16.9%5-year relative survival when found at distant stage (US)

Sources: IARC Global Cancer Observatory (GLOBOCAN 2024) and SEER Cancer Stat Facts, cases diagnosed 2016–2022.

Burden

How common is colorectal cancer, and why is it rising in younger adults?

Colorectal cancer starts in the colon or rectum, usually from a polyp (a small growth on the bowel lining) that turns cancerous over years. GLOBOCAN 2024, the global estimate from the International Agency for Research on Cancer, counts 2,041,007 new cases and 917,895 deaths in 2024: third for new cases and second for cancer deaths. Rates differ about five to six fold between regions and are highest in Europe, Australia and New Zealand, and Northern America. This page is part of the OncoFirm™ Cancer Atlas 2026.

In the United States, an estimated 158,850 people will be diagnosed and 55,230 will die of the disease in 2026. The age pattern is shifting:

  • Younger adults: incidence is rising about 3% a year in ages 20 to 49, while it falls by more than 2% a year in people 65 and older.
  • Share under 65: 45% of new US cases, up from 27% in 1995.
  • Deaths under 50: the American Cancer Society (ACS) calls it the leading cause of cancer death in adults under 50.
  • Late diagnosis: under age 50, 75% of cases are found at regional or distant stage. Only 37% of adults aged 45 to 49 are screened.

The cause of the early-onset rise is not known. The GLOBOCAN authors describe a strong birth-cohort effect: risk climbs with each later-born generation.

Why stage matters

Stage at diagnosis drives survival

Colorectal cancer: five-year relative survival by stage at diagnosisBar chart of five-year relative survival for Colorectal cancer by stage at diagnosis in the United States, 2016–2022: Localized 91.3% survival, 34% of cases; Regional 75.2% survival, 37% of cases; Distant 16.9% survival, 23% of cases. All stages combined: 65.4%. Source: SEER Cancer Stat Facts.COLORECTAL CANCER · FIVE-YEAR RELATIVE SURVIVAL BY STAGE (US, 2016–2022)0%25%50%75%100%Localized34% of cases91.3%Regional37% of cases75.2%Distant23% of cases16.9%All stages combined: 65.4% · SEER Cancer Stat Facts

Colorectal cancer: 5-year relative survival and share of cases by stage, United States, 2016–2022. Source: SEER Cancer Stat Facts (accessed 1 October 2026).

The chart shows 5-year relative survival: the share of patients alive five years after diagnosis, compared with similar people without the cancer. The US SEER registries use three stages: localized (confined to the bowel), regional (spread to nearby lymph nodes or tissues) and distant (spread to other organs).

For cases diagnosed in 2016–2022, survival was 91.3% for localized, 75.2% for regional and 16.9% for distant disease (65.4% across all stages). Only 34% of cases were found while localized; 37% were regional, 23% distant and 6% unstaged. Adults under 50 are diagnosed later, so this all-ages picture understates the early-onset problem.

This gap is the core argument for earlier detection. But finding cancer earlier is not the same as proving fewer deaths. Our early detection evidence hub explains how that proof is judged.

Screening

Screening today: stool tests, colonoscopy and blood tests

As of 1 October 2026, the US Preventive Services Task Force (2021) recommends screening average-risk adults aged 45 to 75. Its list of tests does not include serum (blood) tests. The ACS guideline update of 27 May 2026 also covers ages 45 through 75.

TestDetects cancerDetects advanced precancerInterval and status
FIT (fecal immunochemical test for hidden blood)91%40%Every year
Multi-target stool DNA, next generation93.9%43.4%Every 3 years
Multi-target stool RNA94%46%Every 3 years; FDA approved May 2024
Blood cfDNA test (Shield)83.1%13.2%FDA approved July 2024
Blood cfDNA test (SimpleScreen CRC)81.1%13.7%FDA approved late July 2026
ColonoscopyReference testFinds and removes polypsEvery 10 years

Figures are one-time results against colonoscopy. The blood tests read cell-free DNA (cfDNA), fragments of DNA shed into the bloodstream. They find most cancers but only about 13% to 14% of advanced precancerous lesions, so they detect cancer but prevent little of it. The ACS therefore recommends a blood test only for people who decline or do not complete the preferred tests. Any positive stool or blood test needs a colonoscopy within 6 months.

Two randomized trials show that taking part matters as much as the test. In NordICC (84,583 people, 13 years), an invitation to one colonoscopy lowered incidence (risk ratio 0.81), but the fall in deaths was not statistically significant (risk ratio 0.88). Only 42% of those invited had the exam. In COLONPREV, an invitation to FIT every two years was non-inferior to an invitation to one colonoscopy for 10-year colorectal cancer deaths (0.24% versus 0.22%), and more people took part (39.9% versus 31.8%).

Biomarkers

Established biomarkers by clinical role

A biomarker is a measurable sign of disease or of response to treatment (see cancer biomarkers explained).

BiomarkerTypeUsed forNot used for
CEA (blood)Monitoring, prognosticFollow-up after curative surgery; tracking advanced diseaseScreening or diagnosis
RAS (tissue)PredictiveAnti-EGFR therapy for RAS wild-type, left-sided tumorsScreening
BRAF V600E (tissue)PredictiveEncorafenib plus cetuximab with chemotherapyScreening
MMR/MSI (tissue)PredictiveImmunotherapy first in metastatic diseaseScreening
HER2 (tissue)PredictiveHER2-targeted therapyScreening
ctDNA (blood)PrognosticRelapse risk; genotyping when tissue is unavailableProven trigger for extra treatment

CEA is a monitoring marker. Carcinoembryonic antigen (CEA) is a glycoprotein (a protein carrying sugar chains) made during fetal development and by many colorectal tumors. The US National Cancer Institute (NCI) says it is not a valuable screening test because of its many false positives and false negatives. In 12,349 adults without symptoms in Japan, CEA at a 5 ng/mL cut-off found only 7.8% of gastrointestinal cancers, and 3.7% of positive results were cancers. Smoking, liver disease, inflammatory bowel disease and pancreatitis can also raise CEA.

The established role comes after surgery with curative intent. An ASCO guideline (2013) calls for CEA every 3 to 6 months for 5 years. Accuracy for recurrence depends on the threshold: sensitivity 82% and specificity 80% at 2.5 ng/mL, 71% and 88% at 5 ng/mL, and 68% and 97% at 10 ng/mL. About 30% to 40% of recurrences never raise CEA, so it is paired with imaging. In the FACS trial, CEA follow-up led to more curative-intent surgery for recurrence but no gain in overall survival.

Tissue markers select treatment. The 2026 ESMO guideline for metastatic disease, as summarized in secondary reports, calls for RAS, BRAF V600E, HER2 and mismatch repair (MMR) testing at diagnosis. MMR is the cell’s DNA proofreading system; when it fails, tumors show microsatellite instability (MSI), and immunotherapy is given first.

Key limit. No protein tumor marker, CEA included, is recommended for colorectal cancer screening in the general population.

Serum markers and antigens

Serum protein markers and tumor-associated antigens

Tumor-associated antigens are normal molecules that tumors make in unusual amounts or forms. CEA is one. Two older serum assays, CA 19-9 and CA 72-4, detect tumor-associated sugar structures. In early studies CA 72-4 was raised in up to about 40% of colorectal cancer patients, with specificity above 95%. It is an add-on for monitoring, not a diagnostic test.

The Thomsen-Friedenreich (TF) antigen is a two-sugar unit that is normally an intermediate step in building longer sugar chains. Researchers detect it with peanut agglutinin (PNA), a sugar-binding protein. In one study, 55 of 96 colorectal tumors (57%) were TF-positive by PNA staining. The authors called the work exploratory.

  • Established: serum CEA for monitoring, with CA 19-9 and CA 72-4 as occasional add-ons.
  • Research only: TF, Tn and sialyl-Tn in tissue or blood. We found no prospective study testing them for early detection of colorectal cancer.

Emerging

Emerging approaches in 2025 and 2026

ctDNA for residual disease. Circulating tumor DNA (ctDNA) is tumor-derived DNA in blood, one form of liquid biopsy. After surgery it can reveal molecular residual disease (MRD): cancer too small to see on scans. The prognostic signal is strong, but trials that act on it have had mixed results:

  • GALAXY (observational, 2,240 patients): a positive test after surgery carried about 12 times the risk of recurrence or death.
  • DYNAMIC (stage II, 455 patients): ctDNA-guided care cut chemotherapy use from about 28% to about 15%, with similar recurrence-free survival.
  • DYNAMIC-III (stage III): less chemotherapy for ctDNA-negative patients did not meet the non-inferiority goal (3-year recurrence-free survival 85.3% versus 88.1%). Stronger chemotherapy for ctDNA-positive patients did not help.
  • ALTAIR (phase 3, 243 patients): treating ctDNA-positive patients with trifluridine/tipiracil missed its primary endpoint (hazard ratio 0.79; P=0.107).

As a July 2026 review notes, no treatment step-up triggered by a positive ctDNA result has yet improved survival. More in emerging cancer diagnostic technologies.

Multi-cancer blood tests. As of 1 October 2026, no multi-cancer early detection test is FDA approved. NHS-Galleri, the first randomized trial, missed its primary endpoint: late-stage diagnoses were not reduced (incidence rate ratio 1.03). An FDA advisory panel backed the Galleri test on 23 September 2026; the decision is pending.

AI in colonoscopy. Computer-aided detection raised the adenoma detection rate to 44.8% from 37.4% across 44 randomized trials. The American Gastroenterological Association made no recommendation for or against routine use. See AI in cancer diagnostics and multi-biomarker analysis.

Open questions

Open research questions

  • Why is early-onset disease rising? Diet, metabolic health and gut microbes are suspected, not proven.
  • Can a non-invasive test find precancer? Blood tests miss most advanced precancerous lesions, which is where prevention happens.
  • Do blood tests lower deaths? Unproven. Modeling cited by the ACS predicts less benefit than stool tests or colonoscopy.
  • Can ctDNA guide treatment? The VEGA, MEDOCC-CrEATE and CIRCULATE-North America trials are awaited.
  • Does CEA follow-up extend life? FACS and COLOFOL did not show a survival gain from more intensive follow-up.
  • Do sugar antigens such as TF add anything? Early findings need larger, independent studies.

See also gastric cancer biomarkers.

OncoFirm™ roadmap

Where OncoFirm™ fits, and where it does not

OncoFirm™ is developing a fluorescent lateral flow platform: a test strip read by a small instrument. The assays, reader and software are in development, have not been cleared or approved by the FDA or any other regulatory authority, are for research use only and are not for sale. OncoFirm™ makes no screening claim for colorectal cancer.

CEA assay in development

The CEA assay is designed for 1–100 ng/mL, with planned traceability to the WHO reference preparation for CEA (73/601). That range spans the 2.5 to 10 ng/mL thresholds studied for recurrence monitoring.

Monitoring, not screening

The guideline role for CEA is repeat testing after surgery and during treatment. Any future rapid CEA test would sit there, after comparison with laboratory methods. See the evidence hub.

A number, not a line

Thresholds change the balance between missed recurrences and false alarms, so a quantitative result matters. The platform has a result-time target of 20 minutes or less (a development target).

TF antigen: concept-stage

OncoFirm™ assay concepts for the TF antigen are concept-stage research. Clinical validation is lacking.

OncoFirm™ assays, reader and software are in development, have not been cleared or approved by the FDA or any other regulatory authority, are for research use only and are not for sale. Designed ranges and result times are development targets, not validated performance claims.

FAQ

Frequently asked questions

Is CEA a screening test for colorectal cancer?

No. CEA misses most early cancers and can be raised by smoking or liver disease. In a study of more than 12,000 adults without symptoms, it found fewer than 1 in 10 gastrointestinal cancers. Guidelines use CEA for monitoring, not screening.

What is CEA used for after colorectal cancer surgery?

Doctors measure CEA at regular intervals, often every 3 to 6 months for up to 5 years, to look for signs that the cancer has returned. About 30% to 40% of recurrences do not raise CEA, so it is used together with imaging.

Are blood tests for colorectal cancer screening approved?

Yes. As of 1 October 2026 the FDA has approved two: Shield (July 2024) and SimpleScreen CRC (late July 2026). They detect about 81% to 83% of cancers but only about 13% to 14% of advanced precancerous lesions. The American Cancer Society recommends them only for people who decline or do not complete a stool test or colonoscopy.

Can a ctDNA test tell whether chemotherapy is needed after surgery?

Not reliably yet. A positive ctDNA test after surgery strongly predicts relapse. But as of mid-2026, trials have not shown that adding treatment because of a positive result improves survival.

Does OncoFirm™ sell a colorectal cancer test?

No. The OncoFirm™ CEA assay, reader and software are in development and for research use only. They are not cleared or approved by the FDA or any other regulatory authority and are not for sale.

Sources

References

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  2. International Agency for Research on Cancer. Global Cancer Observatory: World fact sheet, GLOBOCAN 2024. gco.iarc.who.int/media/globocan/factsheets/populations/900-world-fact-sheet.pdf
  3. National Cancer Institute. SEER Cancer Stat Facts: Colorectal Cancer. Accessed 1 October 2026. seer.cancer.gov/statfacts/html/colorect.html
  4. American Cancer Society. News release on Colorectal cancer statistics, 2026 (Siegel RL, et al., CA Cancer J Clin). 2 March 2026. pressroom.cancer.org/rectal-cancer-incidence-rising
  5. US Preventive Services Task Force. Colorectal Cancer: Screening. Final recommendation statement. 18 May 2021. www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening
  6. Wolf AMD, et al. American Cancer Society colorectal cancer screening guideline update. CA Cancer J Clin. 2026. ACS news release, 27 May 2026. pressroom.cancer.org/colorectal-cancer-screening-guideline-update-2026
  7. National Cancer Institute. Colorectal Cancer Screening (PDQ), Health Professional Version. Updated 10 April 2025. www.cancer.gov/types/colorectal/hp/colorectal-screening-pdq
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  9. Freenome. FDA approves SimpleScreen CRC (company news release, 2026); PREEMPT CRC study, JAMA. 2025;334(1):56-63. www.freenome.com/newsroom/fda-approves-freenomes-simplescreen-crc/
  10. OncLive. FDA approves noninvasive stool RNA screening test for CRC (CRC-PREVENT, JAMA. 2023;330:1760-1768). www.onclive.com/view/fda-approves-noninvasive-stool-rna-screening-test-for-crc
  11. NordICC trial, 13-year results of colonoscopy screening. Lancet. 2026;407(10541):1787-1795. www.sciencedirect.com/science/article/abs/pii/S0140673626005088
  12. Castells A, et al. COLONPREV trial of colonoscopy versus fecal immunochemical testing. Lancet. 2025;405(10486):1231-1239. www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)00145-X/fulltext
  13. National Cancer Institute. Colon Cancer Treatment (PDQ), Health Professional Version. Updated 12 February 2025. www.cancer.gov/types/colorectal/hp/colon-treatment-pdq
  14. Sekiguchi M, Matsuda T. Serum CEA and CA 19-9 for cancer screening in 12,349 asymptomatic adults. Scientific Reports. 2020. www.nature.com/articles/s41598-020-75319-8
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  24. Targeted Oncology. FDA advisory panel vote on the Galleri test, 23 September 2026. www.targetedonc.com/view/fda-panel-galleri-multi-cancer-early-detection-test

About this article. Compiled from registry data, guidelines, trial reports and news releases available on 1 October 2026; some trial figures come from secondary summaries and should be checked against the primary papers. Part of the OncoFirm™ Cancer Atlas 2026, written by the OncoFirm™ Scientific Team from the sources linked above and reflecting public information as of 1 October 2026. It is for education and is not medical advice. OncoFirm™ has no affiliation with the companies or tests named. OncoFirm™ assays are in development, have not been cleared or approved by the FDA and are not available for sale.

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