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What is leukemia?
Leukemia is a cancer of the blood-forming tissue — the bone marrow inside our bones, where blood cells are made. In leukemia, the marrow produces large numbers of abnormal white blood cells that crowd out healthy red cells, white cells, and platelets, leading to fatigue, infections, and easy bleeding. Unlike most cancers, leukemia is not a solid lump, so it is treated throughout the body with medicines rather than surgery. Treatment and outlook depend heavily on the exact type — some leukemias are fast-moving (acute) and treated urgently, while others are slow (chronic) and can be managed for many years. Radiation is used in specific, supportive ways, most importantly to prepare the body for a stem-cell (bone-marrow) transplant.
The main types
Doctors group leukemia by where it starts and how it behaves:
| Type | What it means, simply |
|---|---|
| Acute lymphoblastic leukemia (ALL) | A fast-growing leukemia of immature lymphoid cells; the most common childhood cancer, and highly curable in children, also treated in adults. |
| Acute myeloid leukemia (AML) | A fast-growing leukemia of myeloid cells, more common in adults, treated urgently with intensive chemotherapy and often transplant. |
| Chronic lymphocytic leukemia (CLL) | A slow-growing leukemia of mature lymphocytes, often found on a routine blood test; many people live for years, sometimes without immediate treatment. |
| Chronic myeloid leukemia (CML) | Driven by a specific gene change (the Philadelphia chromosome); targeted pills now control it so well that life expectancy can approach normal. |
Staging, in plain terms
Leukemia is not staged with the TNM system used for solid tumors, because it is widespread in the blood and marrow from the start. Instead, doctors classify it by type (acute vs. chronic, lymphoid vs. myeloid) and by risk groups based on genetic and molecular features of the cells, blood counts, and response to treatment — which guide how intensive therapy needs to be.
| Type & risk-based (not TNM) | What it generally means |
|---|---|
| Acute leukemia | Described by genetic/molecular risk (favorable, intermediate, adverse) rather than a number — this predicts response and whether a transplant is needed. |
| CLL (Rai/Binet systems) | Chronic lymphocytic leukemia uses its own systems based on blood counts and whether lymph nodes, spleen, or liver are enlarged, ranging from low to high risk. |
| CML phases | Chronic myeloid leukemia is described in phases — chronic, accelerated, and blast — reflecting how active the disease is. |
| Measurable residual disease (MRD) | Modern care also tracks tiny amounts of leukemia left after treatment using sensitive tests, which helps fine-tune therapy. |
The standard of care
Leukemia is almost always treated by a team that may include a surgeon, a medical oncologist, and a radiation oncologist, combining therapies for the best result. The usual building blocks are:
Chemotherapy
The backbone of treatment for acute leukemias — given in phases to clear the marrow of leukemia cells and then keep it clear.
Targeted therapy & immunotherapy
Pills aimed at specific gene changes (e.g., for CML), antibody and CAR-T cell therapies, and other precision drugs have transformed outcomes for many leukemias.
Stem-cell (bone-marrow) transplant
Replaces diseased marrow with healthy stem cells, offering a chance of cure for higher-risk leukemias; radiation is often part of the preparation.
Radiation therapy
Used in defined roles: total-body irradiation before transplant, treating leukemia in the brain or spinal fluid or a localized mass, easing an enlarged spleen, or relieving symptoms.
How radiation treatment works
Radiation uses high-energy x-rays to damage the DNA of leukemia cells so they can no longer divide. In leukemia its roles are specific. Total-body irradiation delivers a carefully calculated low dose across the whole body to clear hidden leukemia and make room for transplanted stem cells, with shielding to protect the lungs and other organs. Focused radiation can reach leukemia in the brain and spinal fluid or treat a localized mass, using precise planning to spare healthy tissue. Treatments are painless; side effects depend on the dose and area and may include temporary fatigue, nausea, or skin changes, all managed by the care team.
The main ways radiation is delivered for leukemia:
Total-body irradiation (TBI)
Low-dose radiation to the whole body, given with chemotherapy before a stem-cell transplant, wipes out remaining leukemia and suppresses the immune system so donor cells can engraft.
Cranial / craniospinal radiation
Targets leukemia cells that hide in the brain and spinal fluid — a sanctuary chemotherapy reaches less well — used in selected cases such as central-nervous-system involvement.
Localized & palliative radiation
Shrinks a collection of leukemia cells (such as a chloroma), treats an enlarged, uncomfortable spleen, or relieves bone pain with brief, targeted treatments.
Latest studies shaping care
Care keeps improving — often toward getting the same excellent results with less burden on patients. A few developments:
CAR-T cell therapy for ALL: Engineering a patient's own immune cells to attack leukemia produced lasting remissions in children and young adults with relapsed acute lymphoblastic leukemia, a landmark advance.[1]
ELIANA trial, NEJM
Targeted pills for CML: Tyrosine-kinase inhibitors transformed chronic myeloid leukemia from a life-threatening disease into a controllable one, with near-normal life expectancy for many patients.[2]
IRIS trial and long-term follow-up
Refining total-body irradiation: Studies comparing radiation-based and chemotherapy-only transplant preparation help match the gentlest effective regimen to each patient, improving safety.[3]
FORUM trial and modern transplant series
Common questions
Is leukemia treated with radiation like other cancers? Not as the main treatment. Because leukemia is in the blood and marrow throughout the body, medicines are the mainstay. Radiation has important supporting roles — especially total-body irradiation to prepare for a stem-cell transplant, or treating leukemia in the brain.
What is total-body irradiation like? It's low-dose radiation delivered to your whole body, usually in a few sessions over a couple of days, alongside chemotherapy before a transplant. It's painless during treatment; the team manages side effects like nausea and fatigue closely.
Can leukemia be cured? Many can. Childhood ALL is often cured, CML is controlled long-term with targeted pills, and stem-cell transplant offers cure for higher-risk disease. The outlook depends greatly on the specific type and its genetic features.
References
Numbered sources for the studies cited above. Links open the primary publication on PubMed or the publisher’s site.