Leukemia is cancer of the tissues responsible for forming blood, which are immature blood cells found in the bone marrow (the soft, spongy material in the center of most bones). The disease usually starts with an abnormality in the formation of blood cells in the bone marrow. These abnormal cells (or leukemia cells) multiply and outnumber normal cells, preventing their proper functioning.
According to the American Cancer Institute, 61,780 new cases of leukemia and 22,840 deaths from leukemia were reported in the United States in 2019.
Types of leukemia
Leukemias are malignant diseases of white blood cells (leukocytes). This group of diseases is colloquially referred to as “blood cancer”. Leukocytes form an essential component of the immune system and have the task of warding off pathogens and protecting the body from infection.
The blood-forming organ of the body is the bone marrow. There, all cells of the blood are formed and mature in several developmental steps to red or white blood cells as well as platelets. Leukemia occurs when the normal maturation process of the white blood cells in the bone marrow is interrupted or disturbed. Instead of mature, functional leukocytes, more or less immature blood cells are released into the bloodstream. These immature cells can multiply very quickly and uncontrollably, but are usually unable to perform the normal function of white blood cells.
There are several types of leukemia. They can be classified according to the stem cells in the bone marrow from which they develop (myeloid or lymphoblastic) and how quickly the disease progresses (acute or chronic). Leukemia usually refers to cancers of the white blood cells (lymphocytes and granulocytes, the cells responsible for immunity), although some very rare cancers can affect red blood cells and platelets.
- Myeloid leukemia: The disease develops from progenitor cells of the so-called granulocytes, which are important for the fight against infection and can kill germs.
- Lymphatic leukemia: The disease develops from progenitor cells of the so-called lymphocytes, which are involved in the formation of antibodies, among other things.
These two types of leukemia are then categorized into an acute and a chronic form after the course of the disease. Acute leukemia develops very quickly and is usually linked to severe symptoms of the disease. Chronic leukemia develops slowly, often goes unnoticed for an extended period of time and progresses slowly. Based on this classification, four distinct types leukemias are recognized:
- Acute myeloid leukemia (AML)
- Acute lymphocytic leukemia (ALL)
- Chronic myeloid leukemia (CML)
- Chronic lymphocytic leukemia (CLL)
In all the forms of leukemia, uncontrolled growth of immature and not fully functional white blood cells occurs in the bone marrow. Apart from this commonality, they are different diseases, some of which differ greatly from each other in the course and therapy.
Leukemia can occur at any age, with the individual forms having a different age distribution. Acute lymphocytic leukemia, for example, occurs mainly in children and adolescents and is the most common childhood cancer. Chronic lymphocytic leukemia, on the other hand, primarily affects people over the age of 50 and is the most common form of leukemia in adulthood. Essential characteristics of the disease as well as the treatment differ in children and adults.
The causes of leukemia
For the majority of people with leukemia, there is no way to determine the cause. In some cases, however, specific risk factors may be specified:
- A history of chemotherapy or radiation therapy;
- Exposure to high doses of radiation or benzene (a substance found in unleaded gasoline, tobacco smoke and chemical production plants);
- Family history;
- A genetic abnormality, such as an abnormality of chromosome 22;
- Genetic disorders like Down syndrome and Fanconi disease.
All forms of cancer that spread throughout the body (malignant forms), including leukemia, are believed to be caused by genetic abnormalities (mutations).
Symptoms of leukemia
Symptoms of the disease vary depending on the type of leukemia. Symptoms of acute leukemia are usually nonspecific and resemble those of other illnesses such as the flu. They can appear suddenly over a few days or weeks. Symptoms of chronic leukemia, in the early stages of the disease, are very diffuse or even nonexistent. The first symptoms appear gradually:
- Fever, chills, or headache.
- Persistent weakness or fatigue.
- Anemia, which includes shortness of breath, pallor, palpitations (fast heartbeat), dizziness.
- Frequent infections (lungs, urinary tract, gums, around the anus, herpes or cold sores).
- Loss of appetite.
- Sore throat.
- Weight loss.
- Swollen glands, swollen liver or spleen.
- Bleeding (nose, gums, heavy periods) or frequent bruising.
- Small red dots on the skin (petechiae).
- Excessive sweating, especially at night.
- Pain or tenderness in the bones.
- Visual disturbances.
People at risk
- People with genetic disorders. Certain genetic abnormalities play a role in the development of leukemia. For example, Down’s syndrome would be associated with a high risk of leukemia.
- People with blood problems. Certain blood disorders, such as myelodysplastic syndromes (diseases of the bone marrow), can increase the risk of leukemia.
- People who have a family history of leukemia.
- Have undergone cancer treatment. Certain types of chemotherapy and radiation therapy received for different types of cancer can increase the risk of developing certain forms of leukemia.
- Exposure to high levels of radiation. People exposed to high doses of radiation, such as nuclear accident survivors, have a high risk of developing leukemia.
- Exposure to chemicals. Exposure to certain chemicals, such as benzene (a chemical found in gasoline) is said to increase the risk of certain types of leukemia.
- Tobacco. Smoking cigarettes increases the risk of certain types of leukemia.
Certain factors, for example exposure to low-level radioactive radiation, electromagnetic fields or pesticides in young children or during pregnancy could be risk factors for childhood leukemia. However, more research needs to be done to clarify their role in the onset of the disease.
If you consult your doctor with the symptoms mentioned above, he or she will first have a detailed medical consultation with you to accurately record your complaints and medical history. A general physical examination is generally one of the first diagnostic steps. Possible signs of the disease can be swollen lymph nodes as well as an enlarged liver or spleen, so your doctor will mainly scan the lymph nodes and the abdomen.
The next step is a comprehensive examination of the blood to provide information on the composition and ratio of the individual blood components. In leukemia, the number of white blood cells or their (immature) precursors is usually greatly increased, but in some cases it can also be reduced or normal. The red blood cells as well as the platelets, on the other hand, are usually reduced. Blood analysis can also be used to assess which subset of white blood cells has degenerated at what stage of maturity, giving the doctor clues as to what type of leukemia it is.
Not all forms of leukemia have to be found in the blood, but at the same time changes in blood count can also have numerous other causes. In order to confirm the suspected diagnosis of leukemia, the place of blood formation – the bone marrow – must also be investigated. In the context of a so-called bone marrow puncture, a small amount of bone marrow is removed with a fine hollow needle, as a rule the pelvic bone is usually chosen for this. The tissue is then examined in the laboratory under the microscope and evaluated in a fine-tissue (histological) manner. In this way, the diagnosis can be confirmed and precise statements can be made about the form of leukemia you suffer from. The procedure is usually performed under local anesthesia, can be performed on an outpatient basis and takes about 15 to 30 minutes.
With the help of modern laboratory methods (e.g. immunophenotyping), the individual cell types can be further assessed and additional characteristics of the disease can be specified. Knowing the exact type of leukemia is crucial for the planning of the subsequent therapy, since the individual subgroups differ greatly from each other in response to the different treatment options. A chromosome analysis (cytogenetic examination) of degenerate cells is also carried out, as some forms of leukemia are associated with certain mutations. Knowledge of the presence or absence of these mutations can help to further characterize the disease, its possible course and prognosis.
If the diagnosis of leukemia is made, further examinations are usually carried out to determine whether the leukemia cells are located in lymph nodes or other organs or what condition these organs are in. The necessary examination steps are summarized under the term staging. They are important so that your doctor can determine the optimal therapy for you.
In most cases, an ultrasound examination of the abdomen is carried out to assess the liver, spleen and kidneys, among other things. An X-ray of the chest is also often taken. These examinations do not cause you any inconvenience.
A more precise representation of individual organs or lymph nodes is possible by means of a computed tomography (CT) of the abdominal cavity. In this special X-ray examination, sectional images of the examined organs are taken. It lasts only a few minutes and is completely painless.
Magnetic resonance imaging (MRI) is also performed in some cases, primarily to assess the brain and spinal cord. As with CT, cross-sectional images of the investigated area are created, using magnetic fields instead of x-rays. This test, too, is not usually associated with any problems.
If enlarged lymph nodes are found, a lymph node biopsy may be performed to examine the tissue under the microscope. This procedure makes it possible to determine whether the cancer cells are actually present.
In some cases, especially in acute forms of leukemia, an examination of the cerebral spinal fluid (cerebrospinal fluid) is also necessary, as the nervous system could also be affected by cancer cells. In the context of a so-called lumbar puncture, some cerebrospinal fluid is removed with a fine needle at the level of the lumbar spine and then examined in the laboratory. The procedure is often performed under local anesthesia.
Your doctor will talk to you about what examinations are necessary in your personal case and how they will proceed. Once all steps have been completed, your doctor will inform you about the therapeutic steps that can now be taken.
Treatment of leukemia
In the treatment of leukemia, the focus is usually on chemotherapy, in addition radiotherapy as well as new, specific treatment options can be used. Stem cell transplantation can also be performed with appropriate indication.
First of all, which therapy is eligible in your case depends primarily on the type of leukemia. Acute and chronic leukemias are very different diseases, correspondingly the treatments and their processes are also different. The following list is intended to provide an overview of the principle and course of the individual therapeutic options – your doctor will tell you which of these therapies is necessary in your case.
The aim of chemotherapy is to completely destroy the leukemia cells or to push them back as much as possible. Drugs used for chemotherapy (so-called cytostatics) interfere with cell division and prevent cells from growing and multiplying. They are administered in several cycles and attack mainly those cells that divide particularly quickly – primarily damaging the cancer cells. However, healthy, rapidly growing cells are also attacked, often causing undesirable side effects. Your doctor will inform you about the side effects you may have and can help you alleviate them.
Depending on the type of leukemia, different cytostatics are used, often several are combined with each other. The duration and number of individual cycles may also vary depending on the diagnosis; Your doctor will inform you exactly about your individual treatment plan.
In radiotherapy, high-energy (ionizing) rays are used to attack the nucleus of cancer cells. As a result, they can no longer divide and die. Radiotherapy can often halt the progression of cancer and lead to a regression of cancer cells. In leukemia, it is used when there is a risk that leukemia cells are located in the central nervous system, which is poorly reached by most chemotherapy drugs. Targeted irradiation of the brain and spinal cord can often successfully combat these possible settlements.
Also in the so-called conditioning therapy before a stem cell transplant, a whole body irradiation is usually carried out. The required radiation dose is calculated individually. The irradiation takes place in several sessions, whereby the individual treatments themselves are not painful and last only a few minutes. Ask your doctor what side effects you have to expect and how you can alleviate them.
Bone marrow or stem cell transplantation
If chemotherapy shows little or no success, a bone marrow or stem cell transplant can be performed in certain cases. To put it simply, sick bone marrow tissue is replaced by healthy ones. Healthy blood stem cells are transmitted to the affected person, from which all cells of the blood can develop.
Before a stem cell transplant, a very intensive, high-dose, so-called conditioning chemotherapy is necessary. In this process, the entire bone marrow and thus ideally all leukemia cells are completely destroyed. Depending on the type of leukemia, a whole body irradiation is also carried out. The recipient’s immune system is strongly suppressed so that it is not directed against the transplanted cells. Following this high-dose therapy, the healthy stem cells that migrate into the bone marrow mature and develop into functioning blood cells.
In most cases, the stem cells are transferred from a suitable relative or foreign donor (allogeneic transplantation). Under certain circumstances, the patient’s own stem cells can also be taken, separated using special procedures and later returned (autologous transplantation). The donor’s stem cells can basically be obtained from the bone marrow or blood.
For many, a stem cell transplant is the only chance to be cured in the long term. At the same time, however, it is very stressful and risky. The normal function of the immune system often only returns after one year. In the first few months, a prophylactic therapy to prevent a rejection reaction or a so-called graft-versus-host-disease (GVHD), in which the transmitted immune cells attack the body’s own tissue, is obligatory. During this period, those affected are very vulnerable to infection and must comply with special hygiene measures. A stem cell transplant is therefore associated with a longer stay in a specialized center and a very intensive aftercare phase. It is generally possible for all forms of leukemia, but implementation depends on many individual factors and risk and benefits must be carefully weighed in each individual case. Your doctor will have a detailed conversation with you about this option.
Which treatment is right for you
Which treatment options are specifically available to you depends primarily on what type of leukemia you have been diagnosed with. In addition, your age and general health status are also included in the treatment plan.
As a rule, several physicians from different disciplines (e.g. internal medicine, oncology, hematology) are involved in the planning of the individual therapy strategy. This collaboration of different experts is called a tumor board in medicine. This ensures that all important factors are taken into account and that the optimal treatment options are found for you individually.
Your doctor may suggest that you participate in a clinical trial. In specialized centers, new therapeutic approaches are compared with the best available therapies at present. This allows you to receive intensive medical attention and can be an opportunity for you to benefit from new, promising therapies.
A cancer diagnosis is a life-altering event. The diagnosis raises many questions and the situation can seem unmanageable at first. Discuss all your fears and questions with your treating physician at any time. He or she will explain the proposed course of treatment in detail and give you the opportunity to understand everything. This is the only way to make a suitable decision. Your doctor will help you find a way that is also compatible with your personal wishes and ideas.
The treatment options for leukemia have made great progress in recent years, they have become more tolerable and effective. In some cases, there is a good chance of a long-term cure and the quality of life during treatments has also improved. Possible side effects of the individual therapies can often be managed well by appropriate accompanying measures – it is therefore important that you inform your doctor about all complaints. In this way, he or she can support you individually.
Although a complete cure is unlikely for some forms of leukemia, sufferers can usually learn to live well with it. Symptoms that occur can often be reduced and the course of the disease slowed down. Thus, it is often possible to lead an almost normal everyday life despite diagnosis and to return to the earlier quality of life.
The way through the examinations and treatments can require a lot of strength and patience from you at first – always remember that you don’t have to be on your own. Get the help you’re offered. Experts in the field of psychology or psycho-oncology can accompany you through this time. You can also learn how to cope with life with your illness and look forward again through counselling or conversations with other sufferers.
Parlez-vous français? Marquis was born in Paris, France and emigrated to United States at the early age of 5. Nonetheless, he has maintained a strong link to his birth land, speaking French fluently. He graduated from the University of Michigan with a bachelor’s degree in Computer Science and work full-time as a software engineer for a fortune 500 company. Part-time, he covers stories on astronomy and space for the Scientific Origin. In his free time, you’ll find him playing soccer with his pals.