The short answer
An oncologist is a doctor with special training in diagnosing and treating cancer. A hematologist is a doctor with special training in diagnosing and treating blood disorders. Because some cancers are blood cancers, the two roles can overlap, and some doctors do both. Seeing more than one specialist is common in cancer care.
An oncologist has special training in diagnosing and treating cancer.
A hematologist has special training in diagnosing and treating blood disorders.
The roles can overlap, because some cancers are blood cancers, and some doctors do both.
Some oncologists focus on a certain kind of treatment, such as a radiation oncologist who treats cancer with radiation.
Choose how you want to understand this
The full explanation.
The short version
These two specialists have related but different training.
- An oncologist is a doctor with special training in diagnosing and treating cancer.
- A hematologist is a doctor with special training in diagnosing and treating blood disorders.
The names sound different, but their work can overlap. Some cancers are blood cancers, and some doctors are trained in both.
What an oncologist does
An oncologist has special training in diagnosing and treating cancer. Some oncologists focus on one kind of treatment. A radiation oncologist, for example, treats cancer with radiation. So the single word "oncologist" covers doctors with different skills. What they share is a focus on cancer.
What a hematologist does
A hematologist has special training in diagnosing and treating blood disorders. Blood disorders cover many conditions, and most of them are not cancer. So this work is broader than cancer alone. It takes in problems with the blood and with the tissues that make blood, such as bone marrow.
Where the roles overlap
Here is where the two meet. Some cancers, such as leukemia and lymphoma, are blood cancers. They sit right where cancer care and blood disorders come together. So a person with a blood cancer may see a hematologist, an oncologist, or a doctor who does both. The overlap is a normal part of how these fields are organized. It is not a sign that anything is wrong.
A team, not just one doctor
Cancer care usually involves a team, not one doctor. You might see one specialist for one part of your care, and someone else for another part. They share information about your case. It helps to know who is coordinating everything, and who to call with questions.
The bottom line
An oncologist focuses on diagnosing and treating cancer. A hematologist focuses on diagnosing and treating blood disorders. The two overlap for blood cancers. If you are not sure who does what on your team, ask which specialists are involved. Ask what each one handles, and who is your main point of contact.
Sources
Words to know
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Common questions
What is the difference between an oncologist and a hematologist?
An oncologist is a doctor with special training in diagnosing and treating cancer. A hematologist is a doctor with special training in diagnosing and treating blood disorders. Their focus is different, though it can overlap when a blood disorder is a blood cancer.
Why might I see both?
Some cancers, such as leukemia and lymphoma, are blood cancers. Because these sit where cancer care and blood disorders meet, a person may see a hematologist, an oncologist, or a doctor who does both. Cancer care often involves a team of specialists.
What is a radiation oncologist?
Some oncologists focus on a particular kind of cancer treatment. A radiation oncologist is a doctor who specializes in treating cancer with radiation. This is one example of how the general term 'oncologist' can include doctors with different specialties.
Does a hematologist only treat cancer?
No. A hematologist has special training in diagnosing and treating blood disorders, which include many conditions that are not cancer. When a blood disorder is a blood cancer, a hematologist's work overlaps with cancer care.
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Last updated: 2026-08-11Next planned review: 2027-07-14
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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.
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