This is not the first time we’ve talked about blood disorders that are considered hematologic cancers. Myeloproliferative neoplasms, which we have discussed on this blog, would be included in this group.
Leukemia is the most well-known representative of these diseases. Leukemia is a cancer of the blood.
Leukemia is a disease of the bone marrow that causes abnormal production of leukocytes. Depending on the precursor cell of the affected leukocyte, other cell lines produced by the bone marrow may also be affected.
Imagine it like a factory that builds different cells for the body. The higher the error in the production chain, the more resources and space it takes away from the creation of other cells.
There is not only an excess of leukocytes, but also a deficiency in the rest of the blood cells.
Often, these mass-produced cells are immature and/or altered forms, so the patient ironically lacks functional leukocytes.
Additionally, as with other cancers, there is a risk that these abnormal cells may spread to other organs in the body, multiplying the problem.
Abnormal production of what?
Leukocytes, commonly known as white blood cells. We’re going to mention a lot of terms, but don’t worry, there won’t be a test.
This is a heterogeneous group of cells produced in the bone marrow that are the main force of the immune system. They are divided into five cell types, which can be further categorized into granulocytes and agranulocytes (the latter lack specific granules and have a larger nucleus).
All leukocytes come from a common precursor, which is also shared with platelets and red blood cells.
If we follow the production line, granulocytes share another common precursor, the myeloblast. There are three final granulocytes: basophils, neutrophils, and eosinophils. Their names are derived from the type of stain used in microscopy: basic dyes, which do not stain, and acidic dyes like eosin, respectively.
Among the agranulocytes, there are two types, but they do not share a precursor—each has its own:
- Monocytes, which, when leaving the bloodstream and entering tissues, become macrophages. These large cells are known for their ability to phagocytize anything they consider harmful to the body.
- Lymphocytes, which are further divided into Natural Killer (NK) cells and B and T lymphocytes. B lymphocytes mature into plasma cells, or plasmocytes, which produce antibodies.
Based on their lineage, they are sometimes classified as lymphoid (NK cells and lymphocytes) or myeloid (which includes all the others).
Fun fact: Thanks to their functions and variety, leukocytes are the only group of cells found in all tissues of the human body.
Let’s get back to leukemia
Alright, now that we know which cells are problematic, let’s return to the pathology itself.
The classification of the disease is based on the severity of the pathology or the affected cell group:
- By severity: acute and chronic. In acute leukemia, the disease progresses very quickly. Patients usually have a large number of immature cells in the blood, along with some mature cells present before the pathology, but with no intermediate stages of maturation. In chronic leukemia, the disease progresses over months and years, with mature (though abnormal) cells.
- By cell group: Normally, they are classified as lymphoid or myeloid, depending on the affected cell(s).
Both classifications are combined for the terminology of the disease. If we call it chronic lymphocytic leukemia, we are indicating that this leukemia is chronic and of the lymphoid lineage.
Acute forms are more common in children, while chronic forms are more common in adults.
It is estimated that there are about 14 new cases annually per 100,000 people, which represents between 2.5-3% of all cancer cases worldwide. Mortality is similar, estimated at 3% of all cancer-related deaths.
Recorded cases have increased in recent decades, associated with the rise in life expectancy. The age group with the highest number of cases is between 85 and 89 years old.
This could partly explain the much higher incidence, up to 150%, in high-income countries compared to low-income countries, where the average life expectancy is lower.
Incidence and mortality are 40% and 50% higher, respectively, in men than in women. This may be due to the fact that the main environmental risk factors are more common in men, such as being overweight, smoking, inactivity, and hypercholesterolemia.
The decrease in the number of functional blood cells triggers various leukemia symptoms, depending on the damage caused by the disease. These include coagulation problems, an increase in the number and severity of infections, and anemia…
Diagnosis is made through blood tests and cell counts, taking advantage of the altered production of leukocytes. It is confirmed with bone marrow and lymph node examinations.
There are forms of leukemia in which high numbers of leukocytes are not detected in the blood. This is because they remain trapped in the bone marrow, causing damage. A bone marrow examination is essential.
Treatments are the standard ones for cancer: chemotherapy, radiation therapy, medication for symptoms…
Some cases require a bone marrow transplant. This is a disease with much variety, and each patient requires personalized treatment.
Now, focus: Is it hereditary or not?
It’s a complex pathology, so it’s better to talk about predisposition rather than inheritance. While leukemia is not hereditary as such, there is a demonstrated genetic predisposition to it. There is no hereditary leukemia, but there is a hereditary risk of developing it.
Leukemias are always caused by changes in the genetic material of the cell. The key is discovering what triggered those initial changes.
The Philadelphia chromosome, which we have extensively mentioned in the context of myeloproliferative neoplasms, is particularly associated with chronic myeloid leukemia and is considered a risk factor for other types.
Other DNA-related disorders increase the risk of developing leukemia. Down syndrome is a risk factor for many acute forms of leukemia, and the same is true for genetically based anemias.
Typical cancer mutations, such as those in oncogenes or tumor suppressor genes and those linked to the cell cycle, pose a risk for leukemias. Similarly, interaction with carcinogenic substances increases the risk. This latter factor likely contributes to the higher incidence in men than in women.
Some genetic mutations in leukemia involve the TP53, CEBPA, NRAS, AML, CLL, MDS genes… However, depending on the gene, they influence different forms of the disease.
Viruses have been recorded that are capable of causing leukemia. Let’s not forget that many viruses interact with the cell’s DNA when infecting it.
There is a case where we might talk about the heritability of the disease if we want to be particular. Maternal-fetal transmission cases have been detected, in which the baby acquires leukemia because the mother had the disease during pregnancy.
Leukemias are complex and varied, with a large number of genetic and environmental factors involved. And the tellmeGen genetic test helps you stay ahead of the disease.
