What is Leukemia?
Malignant, a frightening word, applies synonymously with cancer, the uncontrolled growth of tissue. Merriam-Webster defines “malignant” as “relentlessly malevolent…tending to produce death…” Cancer is considered a malignancy because it is fatal if not removed, shrunk away, or treated. Even with these strategies, many die from it, when the true meaning of malignancy proves true. Since cancer can arise from almost any type of tissue, it is important to remember that the tissues of blood and blood-making elements are no exceptions. These are called the hematologic malignancies.
Types of blood cells
The blood cells that make oxygen exchange, clotting, immunity, and countless other things possible in the body include:
- Red blood cells (RBCs—erythrocytes, carry oxygen to tissues and exchange carbon dioxide at the lungs).
- White blood cells (WBCs—leukocytes, from where the word leukemia derives, which fight infection). Within the class of WBCs are neutrophils, lymphocytes, monocytes, eosinophils, and basophils. All but the lymphocytes make up the myelodysplastic neoplasms (see below); lymphocytes give rise to lymphocytic leukemia.
- Platelets (thrombocytes, important for clotting).
There is a lot more to blood than just these, but for the purposes of discussing leukemia in general, the RBCs, WBCs, and platelets are a good starting point, since most are of these cell types.
Depending on whether there are RBCs, WBCs, or platelets which undergo a malignant conversion, it means that the normal RBCs, WBCs, or platelets are reduced in number at the expense of the malignant numbers of cells. This results in a functional deficit in the jobs they do:
- anemia (low RBCs)—less oxygenation, resulting in shortness of breath and fatigue
- neutropenia (low WBCs)—less infection-fighting ability, resulting in serious life-threatening infections
- thrombocytopenia (low platelets)—fewer functional platelets, important in clotting, resulting in hemorrhage
Since these cells are made in the bone marrow (indicated by the medical prefix, myelo-), they are called myelodysplastic neoplasms (MDNs).
Is this one disease? Or many?
When people generally think of leukemia, it is MDN they mean, but this is not a useful way to lump together a group of many malignancies. The World Health Organization has classified them based on the type of cell that has undergone malignant transformation. MDNs can be separated into the lymphoblastic leukemia (from lymphocytes, one of the WBC types) or the myelodysplastic leukemias (from all the other types of WBCs). Additionally, the lymphoblastic and myelodysplastic ones can be termed either chronic or acute. Of the two, the acute is the more dangerous, because it generally refers to a conversion into an incurable type.
Lymphocytic leukemia—Acute (ALL—the most common childhood cancer) or chronic (CLL—15-20% of leukemias, and the most common adult leukemia in the USA)
Myelogenous leukemia—Acute (AML) or chronic (CML)
What's the difference between chronic and acute Leukemia?
Chronic leukemia has an excessive amount of abnormal WBCs, closer to normal than what is seen in ALL and AML, but still abnormal. It progresses over time.
Acute leukemia has an increase in bone marrow cell numbers that are so rapid that crowding occurs and the marrow can no longer make normal cells; abnormal cells spill over into the main bloodstream.
Is Leukemia a terminal disease?
Serious stuff: who lives and who dies?
The survival, depending on what type, can range from 2-20 years, with some exceptions. Physical exam and evaluation of peripheral blood usually can give an idea to the seriousness of the disease. Based on the different staging systems, up to 30% live 10-20 years with CLL, with less survival rates applicable to the other leukemias, especially the acute ones.
What are the signs and symptoms of Leukemia in adults?
Since abnormal production of RBCs, WBCs, and platelets occur, the symptoms include:
- Shortness of breath, fatigue, lethargy, weakness.
- Frequent infections, including pneumonias, fungal infections, and sepsis; fevers.
- Easy bruising, nosebleeds, coughing up or vomiting blood and bloody stool.
Is Leukemia curable?
What are the treatments? Can any type of leukemia be cured?
Treatments are the same as with other malignancies: chemotherapy (prednisone, vincristine, anthracycline drugs, cyclophosphamide; radiation, and if necessary, surgery. When remission occurs, more commonly in the chronic leukemias, maintenance therapies can be continued periodically. As far as cures go, although no one is ready to use that word, there have been lengthy remissions with bone marrow transplants and the newer experimental genetic therapies.
Who is the doctor who treats leukemia?
There’s more than just one doctor involved, who is usually a hematologic oncologist; there are nutritionists, radiation oncologists, hematologists, and even psychologists (for the stress and depression associated with severe disease and apprehension over mortality). Since some leukemias occur more often in childhood, pediatricians and pediatric oncologists are involved.
What’s the first step in addressing this problem?
Certainly, maintaining routine visits with a healthcare professional is important, since initial symptoms masquerade as innocent colds, flu, bruises, or fatigue. Under the proper care, if symptoms do not go away based on a simple diagnosis, one must then question the diagnosis and pursue the possibility that something more insidious is going on. This is how leukemia is usually diagnosed. Routine blood work, including a CBC (complete blood count)—the most frequently done blood test in the world—can jumpstart any such suspicions.
Leukemia is a label that represents a cluster of cancers of the blood and blood forming tissues (bone marrow). Since blood manufacture is such a dynamic process, there are many steps that can be made for intervening. No cures are on the books…yet; but given the technology attacking the genetic causes and the advances already in process, lengthy remissions are possible in some of the leukemias, with more being targeted all of the time.
- World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, Swerdlow SH, Campo E, Harris NL, et al. (Eds), IARC Press, Lyon 2008.
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