Leukemia: Symptoms, Types, Causes and Treatment

Leukemia is a type of cancer in which defective lymphocytes are produced uncontrollably in the bone marrow. Due to this, the rest of the blood cells are displaced.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 23 March, 2021

Leukemia is a term that refers to the group of malignant diseases of the bone marrow, a soft tissue found within the bones, where all the circulating cells in the blood are synthesized. It’s the most common type of cancer in children and adolescents, representing 1 in 3 cancers in this age group.

There are many types of leukemia: some are typical of children, while others appear almost exclusively in adults. The prognosis of each patient will depend entirely on the type of cancer, time of detection, age, general health, and many other factors. If you want to know everything about leukemia, read on.

The importance of the bone marrow

Leukemia covers a group of cancerous diseases of the bone marrow. Before investigating the pathology in its entirety, we first need to understand what makes this tissue so special in a normal situation, at least from a cellular and physiological point of view.

Bone marrow is a type of flexible biological tissue found inside long bones, the vertebrae, the ribs, the sternum, skull bones, and the pelvis. This biological conglomerate represents 4% of the body mass of an average human being, a value that ranges from 2.5 to 4 kilograms (5.5 to 8.8 lbs), in a normal situation.

As indicated by the Sanitas portal, hematopoietic stem cells are located in the bone marrow, which are transformed into all circulating blood cell elements when they mature. For this reason, lymphoid cells, myeloids, white blood cells, red blood cells, and platelets originate in this tissue.

The function of the erythropoiesis function in this area is striking. To give you an idea of just how essential bone marrow is, suffice it to say that an average of 500 billion red blood cells are produced there every day. For this reason, diseases that involve these essential structures often have a very poor prognosis.

Leukemia and its types

As the United States National Library of Medicine indicates, the term leukemia means white blood. White blood cells (lymphocytes) are produced in the bone marrow and protect us against infections, but, in this type of cancer, the amount of circulating lymphocytes grows uncontrollably.

The overproduction of defective white blood cells prevents sufficient functional healthy red blood cells, platelets, and white blood cells from being synthesized. As the concentration of circulating elements useful to the body decreases, the patient’s symptoms worsen.

Cancer cells can travel to different parts of the human body, making the initial condition even worse. Beyond this quick and easy definition, it’s important to know that there are many types of leukemia. We’ll tell you the most relevant.

1. Acute lymphoblastic leukemia (ALL)

Acute lymphoblastic leukemia (ALL) is one of the 4 main types of leukemia. In it, there’s an abnormal increase in dysfunctional white blood cells, which are called lymphoblasts. These are defective, so they never mature into functional lymphocytes, and they also displace the rest of the circulating cells in the blood.

This type of leukemia is the most common form of cancer in childhood. ALL constitutes 25% of tumor processes in infants and 75% of total leukemias, a not inconsiderable figure. As indicated by the Integral Pediatrics portal, there’s a slight predisposition for males to suffer from it.

This is a variant with an excellent prognosis, especially if we take into account the severity of the pathology. While previously only 10% of patients survived after treatment, today this figure has risen to 80% with a total remission of the disease. We’ll also look at possible treatments for this cancer later on in this article.

2. Acute myelogenous leukemia (AML)

Acute myeloid (or myelogenous) leukemia is the most common type of leukemia in adults. According to the MSD Manuals portal, it accounts for up to 32% of the total of these types of cancers in general society. In AML, cells of the myeloid line (myeloblasts) proliferate abnormally, gradually invading the bone marrow.

This causes an insufficiency in the production of circulating cells and an infiltration of extramedullary tissues. It’s estimated that 15 inhabitants per million people per year will develop acute myelogenous leukemia in this time interval. The average age of presentation is 64 years, although it’s considered to be common in the 60-75 age range.

3. Chronic lymphoblastic leukemia (CLL)

CLL differs from its acute variant in that, in many cases, the disease progresses slowly and the patient may not notice any symptoms, at least for a few years after the onset of the carcinogenic process.

Chronic lymphoblastic leukemia is also characterized by an accumulation of defective white blood cells, but it progresses more slowly than other types of leukemia. It’s more common in the elderly, and can be treated in a number of ways, as indicated by the Mayo Clinic.

5. Chronic myelogenous leukemia (CML)

In CML, a genetic change occurs in an early, immature version of myeloid cells. This change leads to the mutation of an abnormal gene, named BCR-ABL, which turns the functional myeloid cell into a CML cell. Its growth is slow, but it can transform into an acute variant that’s difficult to treat.

Symptoms of leukemia

We’ll now return to the general premise in these types of cancer: defective lymphocytes are produced en masse, causing a displacement of healthy cell bodies in the blood.

This has multiple physiological effects on the patient’s body, which can be evidenced as follows:

• Fever or chills: These are usually clear signs of infection. When the number of circulating functional white blood cells decreases, the patient is more likely to become infected with viruses and bacteria that previously didn’t affect them
• Repeated infections: The lack of functional white blood cells leads to infections that never seem to remit or that recur over time.
• Swollen lymph nodes, enlarged liver, and spleen: These are indicative that cancer cells have spread to these organs.
• Tendency to bleeding and bruising: The lack of platelets in the blood makes it very difficult for the body to carry out its normal clotting process.
• Excessive sweating, especially at night.
• The appearance of red spots (petechiae) on the skin.
• Bone pain and tenderness.

Weight loss, dizziness, and general malaise are clinical signs that characterize almost any type of cancer.

Faced with any of these symptoms, it’s necessary to go and see a doctor urgently. Most likely, the symptoms aren’t caused by cancer, but it’s always better to prevent it in time than to have to go through the process of curing it.

Causes and risk factors

Despite advances in the field of medicine, the causes of leukemia are still completely unknown, as indicated by the Josep Carreras Foundation.

We know that the incidence is higher in males than in females, especially if we’re talking about people of white ethnicity, but experts haven’t been able to find out exactly why.

Despite not knowing an exact cause in each and every one of the cases, it has been possible to detect register certain predisposing factors to it.

Having undergone previous cancer treatments, having certain genetic disorders, being exposed to certain chemicals, and smoking can lead to the development of leukemia in adult patients.

Treatment

How well a person with leukemia does depends largely on what age it’s detected. For example, only 35% of people over the age of 20 with ALL survive 5 years after diagnosis.

The figure for newborn patients, children, and adolescents (under 20 years of age) is much better, as the survival rate reaches 89%.

However, according to the Cancer.net association, about 4 out of 10 people diagnosed with acute lymphoblastic leukemia (ALL) are adults. In these cases, the prognosis is more variable, as it’s based on the age, general health, general physical condition, and other concomitant pathologies in the patient.

The most common treatments used to fight leukemia are the following:

• Chemotherapy: Certain chemicals are used to destroy cancer cells in the patient. Cytarabine (cytosine arabinoside or ara-C) and daunorubicin (daunomycin) are some of the most common drugs in this type of approach.
• Biological therapy: Various mechanisms are used to “guide” the patient’s immune system, thus making it fight cancer cells.
• Radiation therapy: This uses x-rays or other high-energy beams to kill cancer cells. Radiation can be systemic or local, depending on the extent of the cancer.

Stem cell transplantation

In most cases, chemotherapy, immunotherapy, and radiation therapy can stop the formation of defective lymphocytes, thus relieving symptoms and stopping the cancer from progressing for a long time.

However, even if all clinical signs disappear, there’s a chance that the disease will reappear over time.

Stem cell transplantation is used to replace bone marrow progenitor cells that have been destroyed during disease or treatment.

This transplant can be autogenous (cells from the patient in areas not affected by cancer) or allogeneic, that is, it comes from the bone marrow of a healthy person.

Allogeneic transplantation is always better at a theoretical level, since there’s a risk of collecting cancer cells in an autogenous one. Unfortunately, the patient’s body can reject the donor cells, leading to a number of serious and even life-threatening symptoms. For this reason, allogeneic transplants are not considered in very weak people.

Leukemia is a diverse and complex disease

Leukemia is a type of cancer that causes shudders just when you name it, as it is usually associated with almost certain death.

Fortunately, due to advances in medicine and patient care techniques, it won’t always end in death. Remember that more than 80% of young people with leukemia can be fully cured.

In the case of adult and elderly patients, the prognosis is much more variable, but that doesn’t mean it will necessarily be fatal.

Chemotherapy and radiation therapy can keep the growth of defective lymphocytes at bay, greatly increasing the patient’s quality of life. When faced with cancer, giving up is never an option.