Acute Lymphoblastic Leukemia
Acute lymphoblastic leukemia (ALL) is one of the four basic types of leukemia. It occurs typically in young age by children under 5 years old and by elderly people. It should be noted that prognosis varies – is it possible to cure more than 75% children but on the other hand the effectiveness of therapy by elderly patients is much worse.
The cancer arises from immature hematopoietic cells which serve as precursor cells for some types of white blood cells (in this case for lymphocytes).
Tumor change of a hematopoietic cell is usually a result of chromosomal defects or mutations in their genetic information. These disorders may be very variable but they have one thing in common. They cause the cell to divide uncontrollably and to stop responding to regulatory mechanisms of human body. The reason of such mutation is not exactly known. There certainly is a presence of a genetic precondition combined with outer factors such as chemical or radiation exposure.
Immature tumor lymphoblasts spread to bone marrow, lymph nodes and organs of the body. There are two main problems. Leukemic immature white blood cells can not fulfill their function of immune defense. And what is worse their overproduction suppresses formation of other blood cells (normal white blood cells, red blood cells) and blood platelets.
The symptoms are initially quite nonspecific (fatigue, fever, night sweats, joint pain, loss of appetite, weight loss, etc.). Later because of leukemic cells spread, we can find painless enlarged lymph nodes, enlarged liver, enlarged spleen, and typically bone pain in lower limbs (caused by cancer cell invasion into long bones of lower limbs). The fall in red blood cell numbers becomes obvious and manifests as anemia and anemic syndrome. The lack of function of white blood cells causes repeated infections as a mark of immunodeficiency. Insufficient numbers of blood platelets causes increased bleeding and bruising.
The doctor should focus on discovering the above mentioned symptoms. During examination it is necessary to look for bruises, enlarged lymph nodes and enlarged spleen. Blood tests have a great importance. We look for an increased number of white blood cells. Blood tests can also determine whether this increase is due to high number of immature lymphocytes (lymphoblasts). Better samples than from peripheral blood can be obtained from sternal puncture or better from bone marrow using the so called trephine biopsy. The obtained white blood cells are further investigated, doctors try to discover certain type of leukemic cells and present genetic mutation. It allows them to determine prognosis and start correct treatment. In determining the extension of the tumor process in the body imaging methods can be valuable (chest X-ray, abdominal ultrasound, computed tomography, etc).
Chemotherapy is the treatment of first choice. There are many treatment protocols which are usually divided into three phases. First phase should kill the majority of leukemic cells by a strong chemotherapeutical agent combined with radiotherapy. It is followed by stabilization phase and long-term maintenance phase during which the residue of the disease should be destroyed.
Chemotherapeutical agents are often combined with corticosteroids. It is important to prevent the infestation of brain by cancer cells which is accomplished by its exposure to radiation or application of cytotoxic drugs directly into the cerebrospinal fluid.
It is also possible to perform a bone marrow transplant. It is a risky procedure that, simply told, kills all cancer and healthy blood cells with destruction of the whole bone marrow by very powerful chemotherapy and radiation. After that the patient gets new bone marrow cells from a donor. These cells should spread throughout the body a repopulate and inhabit the bone marrow destroyed by previous treatment. If new cells are not capable of this or when an infection occurs at this stage it is a very serious and often fatal situation.