The short answer
Clonal hematopoiesis means one family of blood-forming cells carries an acquired gene change and has grown larger than its neighbors. It becomes common with age. It is not a cancer, and published follow-up puts the rate of progression to a blood cancer at roughly 0.5 to 1 percent per year.
It describes a clone of blood-forming cells, not a tumor and not a diagnosis of leukemia.
It becomes markedly more common with age: one study found it in 9.5 percent of people aged 70 to 79 and 18.4 percent of those aged 90 and over.
Published estimates put progression to a blood cancer at about 0.5 to 1 percent per year, similar to MGUS.
It can put a mutation into a blood-based tumor test that never came from the tumor.
Choose how you want to understand this
The full explanation.
A clone is not a tumor
Your blood cells all descend from stem cells in the marrow. Over a lifetime, those stem cells pick up small DNA changes. Most changes do nothing.
Occasionally one gives a stem cell a slight edge. Its descendants grow to make up more of your blood than they should. That family of related cells is the clone, and its expansion is clonal hematopoiesis.
There is no lump, no mass, and often nothing wrong with your blood counts. The finding is genetic, not anatomical.
Why this turns up more often after 60
Two large studies published in 2014 measured how common it is.
One sequenced blood from 17,182 people who had no known blood disorder. Detectable clonal mutations were rare below age 40. They appeared in 9.5 percent of people aged 70 to 79, 11.7 percent of those aged 80 to 89, and 18.4 percent of those aged 90 to 108.
The other found clonal hematopoiesis in about 10 percent of people over 65, but only 1 percent of those under 50. In both studies, most of the changes sat in the same three genes: DNMT3A, TET2 and ASXL1.
Sequencing got sensitive enough to see these clones. They were almost certainly always there.
CHIP, CCUS, and the space between them
The word on your report may be one of several, and they are not interchangeable.
- CHIP means clonal hematopoiesis of indeterminate potential. A clone is present, blood counts are normal, and the marrow does not show the cell changes that define myelodysplastic syndromes.
- CCUS means clonal cytopenias of undetermined significance. A clone is present alongside a genuinely low blood count, but without enough evidence for an MDS diagnosis.
- MDS itself is a diagnosis, defined by low counts, abnormal cell shapes and clonal growth together.
The 2015 review that introduced the term CHIP compared it to MGUS and to monoclonal B-cell lymphocytosis. Those are precursor states that are usually benign and usually do not progress.
What the follow-up data actually showed
Two things are true at once, and both belong on the page.
The clone is a real risk factor. It is associated with a higher chance of a later blood cancer, and with higher all-cause death rates, probably through cardiovascular disease.
The absolute yearly risk stays small. The review that named CHIP put the rate of progression to a blood cancer at roughly 0.5 to 1 percent per year, and noted the risk appears proportional to the size of the clone. Its authors state plainly that most people who acquire clonal hematopoiesis with age will never develop MDS.
That is why the size of your clone is worth asking about.
When it is an artifact of a liquid biopsy
This is the version most cancer patients meet, and it is easy to misread.
A blood-based tumor test reads DNA fragments floating in plasma. Some of those fragments come from your tumor. Some come from your blood cells. If a blood cell clone carries a mutation, the test can report it as though the tumor carried it.
In one series of 69 men with advanced prostate cancer, clonal hematopoiesis variants at 2 percent or more turned up in the plasma of 13 men, and 7 had them in DNA repair genes used to decide on PARP inhibitor treatment. Overall the clonal variants accounted for almost half of the somatic DNA repair gene variants found.
The fix is straightforward. Testing plasma alongside a whole blood control sample shows which changes came from blood cells. Ask whether that paired testing was done.
What hematology follow-up looks like
For CHIP with normal counts, follow-up is usually watchful rather than active. Blood counts get repeated, and the clone is noted in your record.
A low count changes the conversation, because that is what separates CHIP from CCUS. Lab Tests for Cancer explains what a blood count measures, and Biomarker Testing and Precision Medicine is a useful list to bring.
Sources
- Steensma DP et al. Clonal hematopoiesis of indeterminate potential and its distinction from myelodysplastic syndromes. Blood. 2015;126(1):9-16
- Jaiswal S et al. Age-related clonal hematopoiesis associated with adverse outcomes. N Engl J Med. 2014;371(26):2488-98
- Genovese G et al. Clonal hematopoiesis and blood-cancer risk inferred from blood DNA sequence. N Engl J Med. 2014;371(26):2477-87
- Jensen K et al. Association of Clonal Hematopoiesis in DNA Repair Genes With Prostate Cancer Plasma Cell-free DNA Testing Interference. JAMA Oncol. 2021;7(1):107-110
Words to know
Tap any term to see what it means.
Common questions
Is clonal hematopoiesis a type of cancer?
No. CHIP is defined as an acquired mutation that drives clonal growth without low blood counts and without the abnormal cell shapes that define myelodysplastic syndromes. The authors of that definition note that most people who acquire clonal hematopoiesis with age will never develop MDS.
How likely is it to turn into leukemia?
The review that named CHIP put the rate of progression at roughly 0.5 to 1 percent per year, comparable to MGUS and monoclonal B-cell lymphocytosis. Risk appears to scale with the size of the clone, so ask what fraction of cells carried the change.
Why did this show up on my tumor test?
Blood-based tumor tests read DNA floating in plasma, and some of it comes from blood cells rather than the tumor. In one prostate cancer series, clonal hematopoiesis variants accounted for almost half of the somatic DNA repair gene variants found in plasma. Pairing plasma with a whole-blood control sample separates the two.
What is CCUS?
Clonal cytopenias of undetermined significance. It describes a clone found alongside a genuinely low blood count, but without enough other features to call it MDS. It sits between CHIP and a diagnosis, and it is a hematology conversation.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Turn this topic into questions for your next appointment.
Speak With Trained Specialists & Human Navigators
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Immediate emergency guidance for fever (>100.4°F during chemo), severe pain, or shortness of breath.
Help Us Improve This Guide
Did this explanation answer your question and help you determine your next step?
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.
Knowledge Check
0 of 3 answered
This self-assessment checks understanding of educational content only. It is not medical advice.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-08-09 what this meansLast updated: 2026-08-11Next planned review: 2027-08-09
How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status — Source checked. This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.
Related articles
Still have questions?
Educational answers, plain language
Free to print and share