Leukemia

Leukemia is a cancer of the blood. It used to be almost a death sentence. Today, the treatment of patients with this diagnosis requires a long and strenuous effort. However, these efforts, thanks to the achievements of modern medicine, are often rewarded with a complete recovery of people.

Today, almost one in two of the 11,000 leukemia patients annually in Germany survive the first five critical years and are considered recovered thereafter.

Leukemia occurs when the progenitor cells of one of the hematopoietic lineages undergo a certain mutation. Due to some of these mutations, cells lose the ability to fully mature and can divide again and again. Soon, due to mutation, diseased cells gain a numerical superiority and crowd out healthy ones. Further complicating the situation is that these cells are so immature that they cannot perform their intended function, that is, they are useless. Over time, they spread throughout the body and replace healthy blood cells. The appearance of leukemia means a disease of the hematopoietic system.

Our blood cells are made in the bone marrow, the spongy tissue that fills the inner cell space of most bones. In young children, blood cells form in almost all bones; in adults - except in cases of significant blood loss - only in certain places: in the bones of the skull, in the vertebrae, in the ribs, in the sternum, in the bones of the pelvis, and only partly in the bones of the upper and lower extremities.

In the bone marrow, absolutely undifferentiated stem cells, hemocytoblasts, are first formed. They multiply in the bone marrow by dividing. During division, new stem cells and so-called progenitor cells are formed. From progenitor cells under the influence of chemical factors, which are currently poorly understood, various blood cells grow. Mature blood cells then pass into the circulatory system. These mature cells, specialized in various functions in the blood, unlike stem cells, can no longer divide. After fulfilling their "duties", these cells die.

In principle, any blood cell can be formed from stem cells: red blood cells to carry oxygen, platelets (or platelets) that cause blood to clot, and a huge variety of white blood cells (or leukocytes) that are part of our immune system. White blood cells include, for example, phagocytes, which capture all foreign agents that have entered the body, such as bacteria. However, in our immune system there are also cells with a specific action that purposefully exchange information and only after that "attack" foreign agents; These cells include a group of lymphocytes.

Definition and enumeration of types of leukemia

What are the types of leukemia?

The term "leukemia" combines many of its individual types, since, in principle, blood cells of any type can "get sick". First of all, there are acute and chronic leukemias:

• In acute leukemia, the mutated cells remain immature and capable of continuing to divide. The consequence of this is a very rapid reproduction of cells that are absolutely useless for the body. This is an extremely dangerous form of leukemia that can be fatal within a few weeks or months.
• In chronic leukemias, cells reach a slightly more mature stage. Sometimes they divide more slowly, and sometimes they can at least partially fulfill their function. Chronic leukemia can remain invisible to the patient for several years, it is sometimes detected only by chance during a blood test.

Another distinguishing criterion is the type of affected blood cells:

• In lymphatic leukemia, lymphocytes, that is, cells of a specific immune system, are affected.
• When myeloid leukemia affects the cells of the nonspecific immune system - granulocytes, which include phagocytes.

Hence the four most common names for leukemias:

• ALL - acute lymphatic leukemia
• AML - acute myeloid leukemia
• CLL - chronic lymphatic leukemia
• CML - chronic myeloid leukemia

ALL occurs primarily in children. Other types of leukemias are mainly diseases of adults. The body's ability to repair genetic defects decreases with age. The likelihood of cancer increases, and hence leukemia. Despite this, according to statistics, leukemia is a fairly rare disease.

With the development of CML, there are three stages of the disease:

• chronic phase
• accelerated phase in which the disease progresses rapidly
• the blast phase (also called the blast crisis phase), in which the disease proceeds as acute myeloid leukemia.

Causes of leukemia

Since the risk factors for leukemia are almost impossible to influence, prevention of this disease is also impossible. To date, experts believe that in most patients, leukemia occurs as a result of a random error in the course of cell division, while the specific trigger for this process has not been identified. On the other hand, there are several known risk factors for developing leukemia. True, they are observed only in a small number of patients. At the same time, not every person who is under the influence of one or more of these factors will necessarily develop leukemia. These factors include:

• high doses of radiation
• chemical compounds, such as certain solvents like the currently banned benzene, or certain cancer chemotherapy drugs (cytostatics)

Human T-lymphotropic viruses, which are the sources of "human T-cell leukemia" - acute leukemia that develops from mature T-lymphocytes. In Europe, these viruses are rare. The infectious diseases they cause occur mainly in Japan, the Caribbean, South and Latin America, and parts of Central Africa. People with certain genetic changes have an increased risk of developing leukemia. This applies, for example, to people with trisomy 21 (Down syndrome).

Symptoms of leukemia

Many symptoms appear due to the fact that patients with leukemia produce too few healthy blood cells, or an excessive number of diseased, leukemic cells interfere with the normal functioning of organs. Which signs indicate the development of the disease depends, among other things, on whether the leukemia is acute or chronic.

In acute leukemia, symptoms appear suddenly, against the background of absolute health. The state of health of the sick can deteriorate catastrophically within a few days. Typical, but at first uninformative symptoms of the disease are:

• weakness, fatigue, pallor
• persistent infections and fever
• frequent nosebleeds and bleeding gums, a tendency to pinpoint hemorrhages in the skin (petechiae), "bruises" (hematomas) and slow blood clotting in injuries.
• lack of appetite and spontaneous weight loss
• bone pain
• swollen lymph nodes in the neck, armpits or groin, as well as an enlarged spleen. The latter may manifest itself, for example, as a feeling of heaviness or pain in the upper abdomen, or nausea and vomiting.
• Due to the large number of white blood cells, other organs, such as the liver, can suffer or increase in size. This can cause a feeling of heaviness in the upper abdomen.
• Possible blockage of small blood vessels. Less commonly, leukemia cells can accumulate in the skin, where they become visible as brownish-red or purple spots, nodules, or vesicles.
• Rarely, damage to the central nervous system is also possible. Patients complain of severe headaches, dizziness, sensory disturbances or paralysis.

Chronic leukemias develop gradually. Their development can continue for months and years before obvious symptoms appear in the sick. Therefore, the disease is often detected by chance, for example, when a doctor prescribes a blood test (study of the “blood picture”) for some other reason. Symptoms of chronic myeloid leukemia (CML) depend primarily on how significant the violation of normal hematopoiesis in patients is. In this case, the following symptoms may appear:

• general and non-specific symptoms for the disease, such as fatigue, pallor, decreased performance, general malaise
• often a significant enlargement of the spleen with a feeling of pressure and fullness or pain in the upper abdomen
• lack of appetite and spontaneous weight loss
• fever with no clear cause
• profuse sweat at night (called night sweats)
• bone pain
• sometimes a tendency to pinpoint bleeding into the skin or the appearance of "bruises", nosebleeds, or bleeding gums
• possible violations of kidney function or involvement in the pathological process of other internal organs

None of the listed symptoms is indicative of the presence of leukemia. And not all of these symptoms should appear at the same time. Therefore, the diagnosis is made solely on the detection of immature cells in the blood and bone marrow.

Symptoms of myelodysplastic syndrome:

• Myelodysplastic syndrome covers various forms of the disease. What they have in common is that the maturation of blood cells is disturbed. Depending on the subtype, red blood cells, white blood cells, blood plastics, or several cell rows are affected. In this regard, the following characteristic symptoms may occur:
• Red blood cell deficiency: "anemia" (anemia) with symptoms such as paleness, fatigue, dizziness, tinnitus, or nausea
• Insufficiency of white blood cells: predisposition to infections due to weakened protection against infectious agents
• Platelet insufficiency: tendency to bleed, increased pinpoint bleeding or "bruising", bleeding gums or nosebleeds.

Diagnosis of leukemia

A diagnostic examination for suspected leukemia in Germany begins with a doctor's question about general well-being, complaints and noticeable changes in the body. This also includes a physical examination, such as palpation of the lymph nodes, liver and spleen. However, in order to reliably establish or exclude leukemia, in any case, it is necessary to examine the blood. Blood is examined by specially trained specialists. The appearance and quantitative ratio of individual blood cells to each other give the first indication of the presence of the disease.

For accurate diagnosis, doctors always examine the bone marrow, in which blood cells are formed. Under local anesthesia, doctors take a bone marrow sample from the pelvic bones. They pierce the skin and puncture the bone at the level of the iliac crest, that is, in the back of the upper part of the ilium. They then suck some of the bone marrow into a syringe through a hollow needle (a procedure called aspiration). Only if this fails, doctors use a large needle to pierce a hole in the bone tissue and take a small cylindrical sample of the bone marrow (biopsy). Like blood, bone marrow is examined in a specialized laboratory. For the modern diagnosis of leukemia, our specialists today also use a number of molecular biological tests. So, for example, with their help, changes in the hereditary information of leukemia cells, which are specific for certain forms of the disease, are studied. It usually takes a few days before the results of these special studies are available.

Depending on the type of leukemia and the symptoms present, additional testing may be needed. To plan treatment, it is important to know how good the general condition of the patient is. Therefore, before starting treatment, in most cases, an assessment of the functional activity of the heart, lungs, kidneys is also carried out, or doctors clarify whether the patient has other diseases. In addition, in order to plan therapy, doctors try to determine how widely the leukemic cells have spread throughout the body. If, in addition to the blood and bone marrow, other organs are also affected, this may cause the appearance of characteristic symptoms and serve as a reason for additional research.

Brain and spinal cord: in acute lymphatic leukemia (ALL) and some forms of acute myeloid leukemia (AML), leukemic cells are sometimes found in the brain or meninges in some patients. Symptoms may include headaches or manifestations of neurological deficits such as paralysis. To detect leukemia cells in the central nervous system, doctors remove some cerebrospinal fluid (CSF) from the spinal canal with a needle. This so-called lumbar puncture, although unpleasant, is not as painful as many patients imagine. In addition to this, local anesthesia of the skin is also performed. The needle is inserted through the skin between the vertebrae of the lumbar spine and gently advanced through the dura, which, along with the cerebrospinal fluid, surrounds and protects the spinal cord. A sample of cerebrospinal fluid is examined under a microscope for the presence of leukemia cells. Magnetic resonance imaging (MRI) may also be helpful if spread to the brain is suspected. On images, you can often see clusters of leukemia cells against the background of healthy brain tissue.

Internal organs: using ultrasound and possibly computed tomography (CT) of the abdomen, doctors evaluate whether the spleen or the liver, kidneys, or intestines are affected by leukemic cells, which may cause these organs to visibly enlarge or change. This can be observed in all forms of leukemia.

Bones: if there is a suspicion that “diseased” bone marrow cells have invaded the bones, for example, when patients complain of bone pain, then an MRI, computed tomography (CT) or scintigraphy is sometimes done to detect changes in the bone tissues. Many of the studies listed here are performed on patients with leukemia, both during and after treatment. Especially, in order to assess the success of therapy and exclude relapses of the disease, blood and bone marrow tests should be constantly repeated and repeated.