Leukaemia: What Causes It and How Is It Treated?

Medical Writer: Oke Ikpekpe, MSc (PH)

Medical Reviewer: Azuka Chinweokwu Ezeike, MBBS, FWACS, FMCOG, MSc (PH)

Highlights

• Leukaemia is a blood cancer that usually begins in the bone marrow, where blood cells are made.
• The four main types are acute lymphoblastic, acute myeloid, chronic lymphocytic and chronic myeloid leukaemia.
• Possible symptoms include persistent tiredness, repeated infections, unusual bruising, bleeding and weight loss.
• Blood tests can show changes that suggest leukaemia. Further tests are often needed to confirm the diagnosis.
• Depending on the type, treatment may involve chemotherapy, targeted medicines, immunotherapy or a stem cell transplant.
• Some people can be cured of leukaemia. For others, treatment can keep the disease under control for many years.

Introduction

Two people diagnosed with leukaemia may have very different experiences. One may become seriously ill within a short time and need urgent treatment, while another may feel perfectly well and only discover the disease through a routine blood test [1].

Leukaemia is a type of blood cancer that can affect both children and adults. Some forms develop rapidly, while others progress slowly, sometimes without noticeable symptoms for years. The type of leukaemia a person has play an important role in the treatment they receive [1,2].

Recognising possible symptoms and getting them checked can help identify the disease. For someone already diagnosed, understanding the type of leukaemia can also make it easier to follow treatment discussions and know what to expect.So, what causes leukaemia, who is more likely to develop it, and what treatment options are available?

What Is Leukaemia?

Leukaemia is a cancer of the blood-forming cells, usually starting in the bone marrow. The bone marrow is the soft tissue inside certain bones that produces blood cells [1,2].These include:

• Red blood cells, which carry oxygen around the body.
• White blood cells, which help protect the body against infections.
• Platelets, which help stop bleeding by forming blood clots.

In leukaemia, some blood-forming cells develop changes in their genes. Instead of growing and developing normally, they multiply abnormally. As these cells build up, there may be less room for healthy blood cells to develop.This helps explain why someone with leukaemia might feel unusually tired, have repeated infections or notice bruises and bleeding without an obvious cause [1,2].

What Are the Main Types of Leukaemia? 

Leukaemia is grouped according to the blood cells involved and whether the disease develops quickly or slowly. The four main types are: [1]

• Acute lymphoblastic leukaemia (ALL): This develops quickly and affects immature cells that would normally become a type of white blood cell that helps fight infections. ALL is particularly common in children, although adults can have it too [1].
• Acute myeloid leukaemia (AML): AML also develops quickly. It affects immature cells that would normally develop into different types of blood cells. Most people diagnosed with AML are adults, particularly older adults [1].
• Chronic lymphocytic leukaemia (CLL): CLL usually develops slowly and affects a type of white blood cell that helps fight infections. It is mainly seen in older adults. Some people feel well at diagnosis and may not need treatment for several years [1].
• Chronic myeloid leukaemia (CML): CML usually develops slowly and affects cells that normally produce different types of blood cells. Most cases involve a chromosome change called the Philadelphia chromosome, which causes leukaemia cells to multiply uncontrollably [1].

What Causes Leukaemia?

Doctors know that leukaemia begins with changes in the genes of blood-forming cells. What they cannot always explain is why those changes occurred in the first place [1,3].Certain exposures and previous health conditions are linked to an increased risk.

• Radiation: Exposure to high levels of radiation can increase the risk of leukaemia. X-rays and CT scans involve much smaller amounts of radiation, although they are not entirely without risk. This is one reason doctors recommend scans when the expected benefit outweighs the risk [3,4].
• Benzene: People exposed to benzene over a long period may have a higher risk of developing leukaemia, especially AML. Benzene can be found in tobacco smoke and in some workplaces where chemicals are used [3,4].
• Previous cancer treatment: Certain chemotherapy medicines and radiation treatments can damage healthy blood-forming cells. In a small number of people, this can contribute to leukaemia developing years after their original cancer treatment [3,4,5].
• Smoking: Cigarette smoking is a recognised risk factor for AML [4,5].

A risk factor increases the chance of developing a disease; it does not mean the disease will definitely occur. Many people diagnosed with leukaemia have none of these known risk factors [3,4].

Who Is More Likely to Develop Leukaemia?

Leukaemia can affect people of any age, but certain types are seen more often in particular groups.

• Children: ALL is most common in young children, especially between 2 and 5 years of age [3].
• Older adults: AML and CLL are diagnosed more frequently in older people [1,3].
• Men: Overall, leukaemia is slightly more common in men than in women [1,3].
• People with certain genetic conditions: Down syndrome and Fanconi anaemia are linked to a higher risk of some types of leukaemia [3,4,5].

The genetic changes that cause most leukaemias develop during a person's lifetime. They are generally not passed down from parents [3,4].

What Are the Symptoms of Leukaemia?

Some symptoms develop over a short period, particularly with acute leukaemia. Others may be less noticeable at first [1,2].Signs to look out for include:

• Persistent tiredness or weakness: A shortage of red blood cells can make you feel exhausted, even after resting [1,2].
• Frequent infections or fever: Leukaemia can interfere with the body's ability to fight infections [1,2].
• Easy bruising or unusual bleeding: You may notice bruises, repeated nosebleeds, bleeding gums or tiny red or purple spots on your skin. These can occur when platelet levels are low [1,2].
• Unexplained weight loss: Losing weight when you have not been trying to [2].
• Night sweats: Sweating enough at night to soak your clothes or bedding [1].
• Bone or joint pain: Aching or pain that may affect different bones or joints [2].
• Swollen lymph nodes or spleen: You might notice swelling around your neck, armpits or groin, or feel full or uncomfortable in your abdomen [1,2].

None of these symptoms is specific to leukaemia. Other illnesses can cause them too. Still, persistent or unexplained symptoms are worth discussing with a doctor.Get urgent medical help if you experience heavy bleeding or severe difficulty breathing. For someone undergoing leukaemia treatment, a fever can be particularly serious. Contact your treatment team immediately if one develops [6,7].

How Is Leukaemia Diagnosed?

A doctor may suspect leukaemia because of your symptoms, examination findings or an unusual blood test result. The next step is to investigate what is happening to your blood cells [1,2,6].

Complete Blood Count

A complete blood count (CBC) is often the starting point. It measures the numbers of red blood cells, white blood cells and platelets.Some people with leukaemia have too many white blood cells, while others have low counts. Red blood cells and platelets may also be reduced. These findings can raise concern, but a CBC alone cannot confirm leukaemia [1,2].

Blood Film (Blood Smear)

A small amount of blood is spread onto a glass slide and examined under a microscope.The laboratory checks the size, shape and appearance of the cells. In some cases, immature cells called blasts may be seen. Their presence can be an important clue, particularly in acute leukaemia [2,6].

Bone Marrow Test

For some patients, doctors need to examine a sample taken directly from the bone marrow, usually from the hip bone.This helps them assess the abnormal cells and is often needed to confirm acute leukaemia. However, CLL and CML can frequently be diagnosed through blood tests without taking a bone marrow sample [1,6].

Flow Cytometry

Not all abnormal white blood cells are the same. Flow cytometry checks for specific markers on these cells, helping doctors determine which type of leukaemia is present [1,2,6].

Genetic and Chromosome Tests

Doctors may also examine leukaemia cells for changes in their genes and chromosomes.These findings can provide more information about the disease and help the treatment team decide which medicines are likely to be useful [1,6].Depending on the symptoms and examination findings, scans or other investigations may be requested [2].

How Is Leukaemia Treated?

Treatment is chosen according to the type of leukaemia and the patient's health. Doctors also look at changes found in the cancer cells, as these can affect which medicines are likely to work [1,6,7].

Chemotherapy

Chemotherapy is commonly used for acute leukaemias such as ALL and AML.The medicines destroy cancer cells or interfere with their ability to multiply. Some are given through a vein, while others are taken by mouth. Treatment may involve several courses, with the schedule depending on the type of leukaemia and how the patient responds [2,6,7].

Targeted Therapy 

Certain leukaemia cells contain genetic changes that can be blocked by specific medicines. Targeted therapy works against these changes rather than treating every cancer in the same way.For example, people with CML are commonly treated with medicines that block the abnormal BCR-ABL1 protein. Targeted treatments are also available for selected patients with ALL, AML and CLL [1,6,7].

Immunotherapy

The immune system normally helps the body recognise and remove abnormal cells. Some leukaemias are treated with medicines that help it attack the cancer.One approach uses antibodies designed to recognise particular cells. Another is CAR T-cell therapy, in which a patient's immune cells are collected and changed in a laboratory before being returned to the body.CAR T-cell therapy is used in selected cases, not for everyone diagnosed with leukaemia [1,5].

Stem Cell Transplant 

A stem cell transplant may be recommended for people whose leukaemia is difficult to treat or has a higher chance of returning.It usually involves giving intensive treatment followed by healthy blood-forming stem cells from a donor. These cells can begin producing new blood cells in the bone marrow.Because transplantation can cause serious complications, doctors carefully consider whether a patient is likely to benefit [1,5,6,7].

Radiation Therapy 

Radiation therapy is less commonly used for leukaemia than for many solid cancers.Doctors may recommend it when leukaemia affects certain areas of the body or as part of the treatment given before a stem cell transplant [1,7].

Watch and Wait 

Some people with CLL are diagnosed before the disease causes any problems.Starting treatment immediately does not always benefit these patients. Instead, their doctor may recommend regular appointments and blood tests. Treatment begins when symptoms, blood counts or other findings show that it is needed.This approach is known as watch and wait or active monitoring [1,6].

Other Care During Treatment 

Treatment is not limited to medicines that attack leukaemia cells.A patient may also need a blood transfusion because of low blood counts, antibiotics for an infection or medicines to relieve side effects [6,7].Follow-up appointments and tests allow doctors to check whether the leukaemia is responding to treatment or whether a different approach is needed [5,7].

Can Leukaemia Be Prevented or Detected Early?

For most people, there is no known way to prevent leukaemia completely. Not smoking and avoiding unnecessary exposure to benzene and high levels of radiation can help reduce certain risks [3,4].

There is no recommended routine screening test for leukaemia in people without symptoms.Sometimes, however, a person has a blood test for an unrelated reason, and the results show an unexpected change in their blood cell counts. Further investigation may then reveal leukaemia [8].This is more likely with slower-growing types such as CLL and CML. Acute leukaemias usually progress more quickly, so people often develop symptoms before the disease is discovered [6,8].

An unusual blood count does not necessarily mean leukaemia. It is a reason for the doctor to investigate further, particularly if the person also has concerning symptoms.

Conclusion

The type of leukaemia matters. It helps doctors decide whether treatment needs to begin immediately, which medicines to use and how closely the disease should be monitored.

If you have been diagnosed, ask your doctor to explain your test results and what they mean for your treatment. Find out which side effects need urgent attention and how your response to treatment will be checked.For anyone experiencing persistent tiredness, unusual bleeding, repeated infections or other unexplained symptoms, getting examined is a sensible first step. These symptoms may have a different cause, but they should not be ignored.

Frequently Asked Questions (FAQs)

1. Can Leukaemia Be Cured?

Yes. Some types of leukaemia can be cured, especially childhood acute lymphoblastic leukaemia (ALL). Others, such as chronic myeloid leukaemia (CML), can often be controlled with treatment for many years.

2. What Happens if Leukaemia Comes Back After Treatment?

When leukaemia returns after remission, it is called a relapse. Further treatment may include different medicines, immunotherapy, or a stem cell transplant, depending on the leukaemia type and previous treatment.

3. Can I Still Work or Go to School During Leukaemia Treatment?

It depends on your treatment and how you feel. Some people can continue working or studying, while others need time off because of tiredness, infections or hospital appointments. Your treatment team can advise you on what is safe.

4. Can Leukaemia Run in Families?

Most cases of leukaemia are not inherited. However, certain genetic conditions can increase the risk. Having a family member with leukaemia does not mean you will develop it.

5. How Is Childhood Leukaemia Different From Leukaemia in Adults?

Acute lymphoblastic leukaemia (ALL) is more common in children, while acute myeloid leukaemia (AML) and chronic leukaemias are more common in adults. Treatment and recovery depend on the leukaemia type, age, and general health.

References

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2. Borkar H. Acute myeloid leukaemia: a review of diagnosis and treatment. RRJ Pharm Pharm Sci. 2023;12:005. Available from: https://www.rroij.com/open-access/acute-myeloid-leukemia-a-review-of-diagnosis-and-treatment.php?aid=93666
3. Tebbi CK. Etiology of acute leukaemia: a review. Cancers (Basel). 2021;13(9):2256. Available from: https://doi.org/10.3390/cancers13092256
4. Ilhan G, Karakus S, Andic N. Risk factors and primary prevention of acute leukaemia. Asian Pac J Cancer Prev. 2006;7(4):515–517. Available from: https://pubmed.ncbi.nlm.nih.gov/17250419/
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6. Chennamadhavuni A, Iyengar V, Mukkamalla SKR, Shimanovsky A. Leukaemia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560490/
7. National Cancer Institute. Acute myeloid leukaemia treatment (PDQ®)–patient version [Internet]. Bethesda (MD): National Cancer Institute. Available from: https://www.cancer.gov/types/leukemia/patient/adult-aml-treatment-pdq
8. Gonzaga Y, Barbara FN, Correia LCL, Migowski A. The unintentional detection of leukaemias with complete blood count. J Am Board Fam Med. 2025;38(2):355–359. Available from: https://doi.org/10.3122/jabfm.2024.240275R2

Disclaimer:
The information provided on this website is for general educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Published October 22, 2026