Leukemia is a type of cancer that affects the blood and bone marrow. It occurs when the DNA of a blood cell mutates and causes the cell to multiply rapidly and fail to die when it should. This leads to an overproduction of abnormal white blood cells that crowd out healthy blood cells. Detecting leukemia can be challenging, especially in its early stages, but modern medical techniques make it possible to diagnose and treat many cases of leukemia.
What is leukemia?
Leukemia refers to a group of cancers that originate in the blood-forming tissues, like the bone marrow. It leads to high numbers of abnormal white blood cells building up in the blood and bone marrow. These abnormal cells interfere with the production of normal blood cells.
There are several main types of leukemia:
- Acute lymphocytic leukemia (ALL)
- Acute myeloid leukemia (AML)
- Chronic lymphocytic leukemia (CLL)
- Chronic myeloid leukemia (CML)
Acute leukemias progress quickly and require prompt treatment. Chronic types tend to progress more slowly.
Leukemia is the most common type of cancer in children, but it can occur at any age. Factors that can increase the risk of developing leukemia include:
- Genetic disorders like Down syndrome
- Exposure to high levels of radiation
- Prior chemotherapy or radiation treatment
- Smoking
- Exposure to certain chemicals like benzene
- Family history of leukemia
However, in many cases, there is no identifiable cause.
Signs and symptoms
Some common signs and symptoms of leukemia include:
- Fatigue and weakness
- Frequent infections
- Fever and chills
- Easy bleeding or bruising
- Bone pain
- Swollen lymph nodes
- Excessive sweating, especially at night
- Unintentional weight loss
- Appetite loss
- Shortness of breath
- Pinpoint red spots under the skin
- Abdominal discomfort from an enlarged spleen
However, these symptoms are vague and often mirror those of other, less serious conditions. This makes leukemia detection challenging in early stages. A person may feel slightly unwell for some time before seeking medical evaluation.
Why early detection matters
Detecting leukemia early in its course leads to better outcomes. When it is caught and treated early, many patients can achieve long-term remission. Treatment is also less intense compared to more advanced disease.
But if leukemia remains undetected, it can quickly spread throughout the blood and to other parts of the body. The accumulation of abnormal cells will crowd out healthy, functioning blood cells. This leads to the signs and symptoms of leukemia getting progressively worse. Complications like severe infections and bleeding problems can also appear.
Without treatment, leukemia is usually fatal within several months to a few years, depending on the type. Even with treatment, survival rates are lower when leukemia is more advanced at diagnosis.
How is leukemia detected?
The gold standard for diagnosing leukemia is examining blood and bone marrow samples under a microscope. This allows doctors to see if abnormal white blood cells are present. They can also test for certain cell features and genetic markers to determine the type of leukemia.
Some common tests used to detect leukemia include:
Complete blood count (CBC)
This basic blood test provides an overview of the numbers and types of cells present. In many leukemias, high white blood cell counts with many immature cells are seen. Low red blood cell and platelet counts may also occur. While a CBC alone is not enough to diagnose leukemia, it can provide the first indication leading to further testing.
Peripheral blood smear
Looking at a smear of blood under the microscope provides information about the numbers and shapes of the different cell types. In leukemia, abnormal white blood cell morphology and high counts of immature cells called blasts are typically seen.
| Normal Blood Smear | Leukemia Blood Smear |
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Bone marrow biopsy and aspiration
This procedure collects a sample of bone marrow, usually from the hip bone. The marrow is examined to see if leukemia cells have invaded this vital blood-forming tissue. Doctors also analyze the shape and maturity of cells, chromosome changes, and chemical markers within the sample.
Immunophenotyping
This method uses antibodies to identify specific proteins on the surface of leukemia cells removed from the blood or bone marrow. Determining the cell’s immunophenotype – its protein fingerprint – aids leukemia classification and guides treatment.
Genetic testing
Techniques like fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) detect genetic abnormalities and mutations within leukemia cells. This information helps determine the leukemia subtype and prognosis.
Lumbar puncture (spinal tap)
In acute leukemias, doctors may also examine the cerebrospinal fluid around the brain and spinal cord to see if leukemia cells are present. This helps determine if the cancer has spread to the central nervous system.
Role of imaging tests
While imaging like x-rays, CT scans and PET scans have a limited role in direct leukemia detection, they still provide valuable information by showing if the lymph nodes, spleen or other organs are enlarged. Ultrasound can also detect organ swelling and help guide needle placement for bone marrow biopsies.
How hard is it to detect leukemia?
The ease of detecting leukemia depends on the specific type as well as individual factors:
Acute vs. chronic leukemia
Acute leukemias like ALL and AML tend to announce themselves relatively quickly with symptoms like fatigue, fever and bleeding. Large numbers of abnormal cells spill out into the bloodstream from the overcrowded bone marrow. This makes acute leukemias somewhat easier to pick up on blood tests compared to chronic forms.
Chronic leukemias like CLL and CML develop slowly. People may feel well for years as the abnormal cells gradually accumulate. Annual blood counts done as part of routine physicals eventually show elevated white cell counts. But without overt symptoms or routine screening, chronic leukemias can go undetected for some time.
Childhood vs. adult leukemia
Leukemia is the most common childhood cancer, so pediatricians have a high degree of suspicion if symptoms and blood test results are concerning.
Leukemia becomes less common in teens and adults. Since symptoms like fatigue and infections are nonspecific, it may take longer to consider and test for a possible leukemia diagnosis. However, the wide availability of blood testing facilitates detection once concerning findings are noticed.
Individual factors
Some people are more prone to downplay early symptoms and delay seeking medical care. This can lead to more advanced disease at diagnosis. Factors like lack of health insurance or access to regular providers can also impede early leukemia detection.
But ultimately, the signs and symptoms combined with abnormalities on blood tests like the CBC provide the necessary clues to prompt further evaluation and specialized testing to identify leukemia.
Conclusion
Detecting leukemia early in its course leads to better outcomes compared to more advanced disease. However, some of its early symptoms like fatigue, fever and bruising are vague and mimic other conditions. This makes the diagnosis challenging in initial stages, especially in adults. Acute leukemias tend to manifest symptoms more rapidly compared to more indolent chronic forms. But modern lab testing makes it possible to catch most cases of leukemia if concerning findings prompt additional diagnostic testing like bone marrow examination. Patients also play a key role by recognizing subtle health changes and seeking prompt medical care for evaluation.