In the previous articles we read about the basics of cancer, and in detail about colorectal and pancreatic cancers, and as a continuation, in this article let’s see about leukemia.
Leukemia is one distinct type of cancer that prevails in younger age groups. It is the most common cancer of childhood, moreover, this is a type of cancer that begins in the stem cells that are found in the bone marrow. Leukemia is considered as a malignant disordered of the hematopoietic stem cells compartment, characteristically associated with an increased number of white cells in the bone marrow or peripheral bloodstream.
EPIDEMIOLOGY OF LEUKEMIA :
Though leukemia is a cancer of childhood, adults constitute the majority of leukemia patients.
Leukemia constitutes about 2.5% of the overall occurrence of cancer
3.5% of deaths from cancer are due to leukemia.
Causes of leukemia…….
- Radiation (X-ray) – mostly ionizing forms
- Chemical exposure- Benzene, cytotoxic drugs, etc.
- Chromosomal abnormalities- Ph chromosome
- Viruses like the retrovirus
- A combination of genetic and hereditary factors are responsible
What is leukemia and how does that affect the body?
To answer this question we need to know what stem cells are.
Stem cells considered primitive or undeveloped cells. They possess the potential to develop into specialized cells of the organs in the future. But in some tissues they continue to divide into new stem cells throughout development and into adulthood, in order to frequently generate new cells, thus helping us to keep up with the body’s needs.
In the bone marrow, the stem cells differentiate into many types of blood cells. Some of them include the.
RED BLOOD CELLS :
The red blood cells of the body carry oxygen to various parts of the body and hence keep them perfused.
WHITE BLOOD CELLS:
The white blood cells are the warriors of the body. They make up the immune system. They fight and protect our bodies from various infections.
The platelets are small cells that protect us from bleeding out. They form small plugs by sticking up to one another. Thus, blocking the injured and bleeding blood vessels.
All these types of cells replicate and continue to carry out their function. Meanwhile, this takes place in a harmonious manner. Every once in a while this cell production and replication process go awry and defective cells with certain mutations are produced. These types of cells with defective DNA material are supposed to self destroy themselves; (through apoptosis). Apoptosis is nothing but ‘programmed cell death.
Certain cells do not follow this order. They continue to mutate and further give rise to a lot of mutated cells. Even though, these cells lose their original function.
One theory that explains the occurrence of leukemia is
- They are often caused by just one or two DNA modifications, while a lot of other types of cancers require many changes in the whole genetic buildup. This explains why leukemia has a faster development. And, spread faster than many other types of cancers.
The other reason explained is, some DNA alterations can occur in white blood cells during the development of the fetus in the womb. This increases the risk of early leukemia.
Once leukemia sets in the damaged cells (mutated ones) reproduce in the blood and bone marrow. This process continues until these cells take up all the space within the bone marrow. When the bone marrow can no longer produce the needed functional cells the real problem arises.
The depletion of RBCs causes reduced oxygen supply to parts of the body like muscles, organs, etc. and similarly, the depletion of platelets causes the insufficiency of cells to repair wounds. A reduced number of WBC’s impairs the ability of the body to fight a majority of infections.
SYMPTOMS OF LEUKEMIA:
Leukemia, like many other cancers, is diagnosed in the later stages. The symptoms of leukemia are vague and difficult to understand. Some of the symptoms that might show up in patients with leukemia include,
- Chronic unexplained serious infections (due to reduced number of WBC’s)
- Shortness of breath
- Bruising or bleeding (due to reduced number of platelets)
- Bone or joint pain
- Petechiae (small pinpoint bleeding spots are seen through the skin) – initially confined to the lower part of the body like the knees, ankles feet, etc.
- Swollen lymph nodes
- Enlargement of the liver or the spleen
- Lack of proper sleep or oversleeping
- Remember the pneumonic ‘TEST’.
T- Tiredness and exhaustion
E- Excessive sweating (night sweats and fevers)
S- Sore bones and joints
T- Terrible bruising and unusual bleeding
All the above said are some of the symptoms of acute leukemia. On the other hand, patients with chronic leukemia might be quite unaware of the situation for a long duration. They might be diagnosed during a routine blood test for other symptoms and an elevation of the white blood cells is quite common. Further probing might reveal leukemia. In addition to the elevated white blood cells, some of the above said symptoms are common.
TYPES OF LEUKEMIA:
There are 4 major types of leukemia,
- Acute Lymphocytic Leukemia (ALL)- around 2-4 years of age
- Chronic Lymphocytic Leukemia (CLL)- around 50-70 years of age
- Acute Myelogenous Leukemia (AML)- peaks at 60 years of age
- Chronic Myelogenous leukemia (CML)- the incidence of occurrence increases with age.
History and physical examination is mandatory. The other tests include,
- Routine blood tests were done over a period of time (Complete blood count and blood film)- to check out for anemia, leukocytosis, and thrombocytopenia. Blood films are done to examine the type of leukemia the patient suffers from.
- Bone marrow biopsy
- Immuno-phenotyping (not done on a regular basis)
- Genetic testing
- Gene mutations testing
- Karyotyping (Fluorescent in-situ hybridization)
- Imaging (CT to ultrasound)- enlargement of lymph node or spleen liver.
A combination of the above-mentioned tests is done to diagnose leukemia.
Leukemia is tricky to treat unlike other types of cancer. Leukemia is not a solid tumor to resect or remove through surgery. The cancerous cells in leukemia are completely spread throughout the body.
As we have read in the previous articles, a widespread form of cancer requires treatment modalities like chemotherapy. Chemotherapy involves using a combination of various drugs to kill the offending cells and prevent further growth. While treating leukemia there are three main goals or rather phases that we should follow in order.
1st phase – INDUCTION
The phase where the drugs are administered rigorously according to the stage of cancer and the patient’s needs. This phase goes on for 4 weeks. Done to kill the cancer cells. Although, the cells might not be killed within 4 weeks. The process might take its own time according to the patient’s body condition, existing co-morbidities
2nd phase- CONSOLIDATION
In this phase,
We aim to kill the remaining leukemic cells that were left out during the phase of induction.
Further, preventing the spread of cancer to the brain through the cerebral spinal fluid (CSF)
3rd phase- MAINTENANCE
This is the last phase of chemotherapy. A low dose of the drug is administered for a duration of 2-3 years. This phase is usually followed to avoid remission of cancer.
But, on the other hand, the drugs used in chemo do not differentiate between a healthy normal functioning cell and a cancerous cell. Hence, once it sets inside the body it kills a large amount of cell population (both healthy and cancerous). Thus it kills many vulnerable cells like those that make up the hair follicles, pancreas, etc. This process for longer periods of time leads to issues like bone marrow suppression where the healthy cells of the bone marrow are killed and the bone marrow is unable to produce new cells.
Bone marrow transplantation is the answer to these issues.
‘Bone marrow is a semi-solid spongy tissue inside the bone that replenishes blood cell’. The bone marrow helps in the production of young red blood cells that later develop into matured ones.
It involves replacing bone marrow that has been damaged due to surgery, radiation, chemo, or any disease process. Involves transplanting blood stem cells, which travel through the bone marrow and thus promote the growth of the marrow.
It is a non-surgical procedure to
- Infuse healthy stem cells
- Replace cancerous or faulty blood cells
The blood and bone marrow transplant (BMT):
Done using stem cells from either the bone marrow, blood (peripheral stem cells), or umbilical cord.
The types of bone marrow include
- Autologous transplant (using self donated cells)
- Allogenic transplant (using stem cells from matched- related or unrelated donors; half-matched or haploidentical donors)
Haploidentical donors- stem cells collected from half-matched donors. (usually from a parent, sibling, child, or an unrelated donor).
However, finding a perfect donor for bone marrow transplantation is not a cakewalk. Even the closest of relations and siblings do not match for a transplant most of the time.
Bone marrow transplantation demands antigen compatibility between the recipient and the donor. This is essential to keep the transplanted cells from attacking the patient’s own cells as foreign bodies. Unlike, the usual blood transplants, bone marrow transplants have thousands of HLA types. Searched on a huge platform containing the genetic makeup of millions of voluntary bone marrow donors. This wider search might help us to find a suitable donor and save the life of the person affected by leukemia.
Bone marrow transplant is successful in 80% of Indian patients and almost 17,500 people benefit from bone marrow transplants in a year.
Steps in performing a bone marrow transplant include
Step 1: ‘Preparation’
- The first stage of preparation is finding the ‘right donor’.
- The next step is collecting the stem cells from the donor
Step 2: ‘Conditioning’
Cycles of chemotherapy or radiotherapy take place.
Step 3: ‘Transplant’
- Infusing stem cells into the patient. Done using a central venous catheter, which is nothing but a long, thin flexible tube.
- The targeted blood count by continuous blood transfusions.
Step 4: Checking for engraftment.
- Cancer-free, healthy blood cells begin to grow
- After this regular blood tests and transfusions until full recovery is mandatory.
- It might take 2-6 weeks for the normal blood count to return
Time taken for recovery:
- In case of allogenic transplants it might take about 3-6 months for recovery
- On the other hand, for autologous transplants, the period of recovery might take 12- 18 months
Some of the precautions that have to be taken after a bone marrow transplant include,
- Taking the prescribed medications at the proper time.
- Avoiding potential sources of infection by means of,
- Frequently washing the hands
- Wearing masks
- Avoiding crowded places
It is important to avoid any major allergic reaction and graft or organ rejection (achieved through immune-suppresion). This is the reason why avoiding any form of infection after transplant is essential to stay safe and avoid the further burden.
- Having a healthy and well-balanced diet
- Maintaining personal and oral hygiene.
Apart from its use in leukemia and myeloma (blood cancers), the bone marrow transplant is also a choice in,
- Cancers of the bone marrow
- Cancers of the lymph nodes
- Non- cancerous blood diseases like aplastic anemia, sickle cell anemia
Hence, chemotherapy and bone marrow transplantation remain the major form of treatment for leukemia. The type of leukemia the patient is suffering from is also important. Age plays a major role. Hence, it is good to look up and get ourselves tested when any of the above symptoms show up and get the blood levels tested at regular intervals to avoid any complications.