Leukemia: what types are there and how are they diagnosed

What is leukemia?

Leukemia is a cancer of the blood (white blood cells). It occurs when healthy blood cells, which form in the bone marrow, change and grow out of control. These blood cells circulate through the lymphatic system and bloodstream.

The abnormal white blood cells replace healthy blood cells and make it difficult for the blood to perform its function.

What types of leukemia are there?

Depending on the time of onset of the cancer, it is designated as follows:

  • Acute leukemia: it is characterized as abrupt.
  • Chronic leukemia: in this case it is more progressive.

How is it diagnosed?

A routine blood test may be the first sign that alerts specialists, in the event that an abnormal level of certain blood cells is detected. This is usually the most common way to detect cases of chronic leukemia.

Routine examinations should be performed as often as recommended in order to make an early diagnosis of cancer.

In order to have a definitive diagnosis, an exhaustive blood test must be performed. In this test the cancer cells will be isolated to know their morphology and genetic, immunophenotypic and molecular characteristics. There are situations in which, additionally, a bone marrow study may be needed, either by biopsy or bone marrow aspirate.

Symptoms of leukemia

Apart from the blood test, there are some symptoms that may facilitate the detection of cancer:

  • Persistent fatigue (for weeks or months) for no apparent reason.
  • Easy bleeding.
  • Persistent enlargement of a lymph node.
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Types of chronic leukemias

There are multiple subtypes of chronic leukemias but, mainly, two are distinguished:

  • 1. Chronic lymphocytic leukemia (CLL)

In CLL, the bone marrow, instead of making healthy cells, makes abnormal white blood cells. It is the most common type of blood cancer, common in the elderly. It practically never affects children.

It is diagnosed when too many abnormal lymphocytes are detected in the blood. Because in most cases no symptoms are detected (80%), it is usually diagnosed by chance. Once the disease progresses, there are the following symptoms:

  • Fatigue
  • Anemia
  • Bleeding (due to decreased platelets)
  • B symptoms (weight loss, fever ≧38°C, night sweats).
  • Infections
  • Enlarged lymph nodes.

Half of patients with CLL do not require treatment, as it is a relatively benign and slowly progressive disease. Other patients may require treatment during periods when the leukemia is more active, in order to control symptoms.

This treatment is based on immunochemotherapy or chemotherapy schemes.

  • 2. Chronic myeloid leukemia CML

In CML, the bone marrow makes abnormal white blood cells instead of healthy cells. These abnormal cells are myelocytes instead of lymphocytes. It is a common disease in middle age and accounts for 15-20% of leukemias.

It is usually detected by chance (in 60% of cases), as the patients have no symptoms, since it is a pathology that develops very slowly.

As soon as the disease progresses, the following symptoms can be detected:

  • Sweating
  • Weight loss
  • Fever
  • Abdominal discomfort
  • Anemia
  • Asthenia
  • Bleeding

Chronic myeloid leukemia always needs treatment. It is currently based on the administration of a tyrosine kinase inhibitor (TKI), which differs from chemotherapy in that it only attacks the tumor cell, instead of the healthy cells. This treatment has a very high and prolonged response rate, so allogeneic transplantation is reserved for cases of young patients in advanced stages of the pathology or for those in whom the TKI does not work.

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Follow-up after treatment of chronic leukemia

In most cases patients require permanent treatment. Those who are able to discontinue treatment should follow periodic controls consisting of:

  • Physical examinations
  • Bone marrow and/or blood tests
  • Imaging tests

Imaging tests should be done every three months during the first year to check that the leukemia does not recur and, if it does, to detect it in time.

As the years go by, the frequency of follow-up tests decreases, down to an annual check-up (in the fifth year). Due to the chronic nature of leukemia, checkups should be maintained throughout the patient’s life.