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 — because 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 a particular kind of cancer treatment. For example, a radiation oncologist is a doctor who specializes in treating cancer with radiation. So the single word "oncologist" can include doctors with different specialties, all centered on cancer.
What a hematologist does
A hematologist has special training in diagnosing and treating blood disorders. Blood disorders include many conditions, and not all of them are cancer. So a hematologist's work is broader than cancer alone — it covers problems with the blood and blood-forming tissues.
Where the roles overlap
Here is where the two meet: some cancers, such as leukemia and lymphoma, are blood cancers. These sit right where cancer care and blood disorders come together. Because of that, 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, not a sign that anything is wrong.
A team, not just one doctor
Cancer care often involves a team of specialists rather than a single doctor. You might see one specialist for one part of your care and another for a different part, and they share information about your case. It helps to know who is coordinating your care and who to contact with questions.
The bottom line
An oncologist focuses on diagnosing and treating cancer; a hematologist focuses on diagnosing and treating blood disorders; and the two overlap for blood cancers. If you are not sure who does what on your team, ask which specialists are involved, what each one handles, and who is your main point of contact.
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: 2026-07-14Next planned review: 2028-07-13
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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 verified — This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.
Human medical review: not completed. Cancer Explained is not clinician-reviewed, and that is a deliberate design choice rather than a gap we are waiting to close. We restate published federal guidance and cite it; the authority belongs to the source, not to us. That is why every page names where its claims come from — so you can verify us instead of trusting us. Use it to understand your situation and to ask better questions of the people treating you.
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