Blood Cancer: What Leukemia Is, Types, and Diagnosis

A person often hears the words "blood cancer," "leukemia," "leukosis," and "white blood" on the same day — and does not always understand that they refer to one circle of diseases. Below is a calm explanation: what happens in the bone marrow, what types of leukemia exist, and what the path to a diagnosis looks like.

Blood cancer: what it is and how leukemia, leukosis, and "white blood" are related

Leukemia is a clonal malignant disease of the hematopoietic system; this word unites a broad group of diseases that differ in origin. Leukosis is another name for leukemia; the word "white blood" is used in conversation, although it is not always present in leukemia. "Blood cancer" and "bone marrow cancer" are colloquial expressions. Leukemia begins in the blood-forming tissues, primarily in the bone marrow, so it is not a tumor of a single organ but a disease of the entire blood system.

Leukemia is cancer: what happens in the bone marrow

The bone marrow produces cells from which leukocytes, erythrocytes, and platelets develop. White cells help fight infection, red cells deliver oxygen from the lungs to tissues and organs, and platelets participate in forming a clot that stops bleeding. In leukemia, the bone marrow produces many abnormal cells — most often white cells. They accumulate in the bone marrow and blood, displace healthy cells, and the blood stops performing its tasks. Tumor tissue grows in the bone marrow and replaces normal hematopoietic lineages — hence increased bleeding, hemorrhages, and immune suppression with infectious complications.

Types of leukemia and stages

The type of leukemia depends on which blood cell became tumorous and how quickly the disease grows. The cells may be lymphocytes — a type of white cell — or myeloid, that is, immature precursors of white cells, erythrocytes, and platelets. Acute leukemia grows quickly and, without treatment, usually worsens rapidly; chronic leukemia grows slowly and worsens over a long period. There are four main variants: acute lymphoblastic — the most common cancer in children, and it also occurs in adults; acute myeloid — more often in older people, and it also occurs in children; chronic lymphocytic — one of the most common in adults, often in middle age and later; chronic myeloid — usually in middle-aged and older adults. The classification of leukemias is based on the cell type and the rate of the disease, and after diagnosis additional tests are ordered to see whether other organs are affected.

Causes and risk factors

Leukemia occurs when the genetic material (DNA) of bone marrow cells changes. Science does not yet know the cause of these changes. Factors associated with increased risk have been described: certain types of chemotherapy and radiotherapy, individual genetic disorders, exposure to a number of chemicals, smoking (increases the risk of acute myeloid leukemia), and cases of leukemia in the family. Risk increases with age: the disease is more common after age 60, and the set of factors differs for individual types.

How leukemia is diagnosed

Diagnosis begins with an examination and conversation: the doctor takes a medical history. Next are blood tests, including a complete blood count with cell counts. If the picture is concerning, the bone marrow is examined: aspiration (sampling the liquid part) and biopsy (sampling a piece of bone) are performed — more often from the iliac crest or via sternal puncture. Samples are sent to the laboratory: morphological examination of blood smears and bone marrow biopsies is of great importance in diagnosing leukemias. Genetic tests look for changes in genes and chromosomes. Once the diagnosis is made, imaging studies and a lumbar puncture may be ordered — sampling cerebrospinal fluid to understand whether other organs are affected.

When to see a doctor

Reasons to talk to a doctor include the following signs:

• fatigue that does not go away after rest;
• fever or night sweats;
• bruises appear easily, bleeding is hard to stop;
• loss of weight or appetite;
• petechiae — small red dots under the skin due to hemorrhages.

In chronic leukemia, there may be no symptoms at first — then the first signal is changes in a blood test. A doctor should assess complaints and order examinations.

A diagnosis of leukemia is not in itself a reason to call an ambulance; 103 or 112 — for a life-threatening condition, for example bleeding that cannot be stopped.

This material is for reference and does not replace consultation with a doctor.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer