Understanding Leukemia: When Immune Cells Turn Against Us
White blood cells are cells in the body’s immune system that help fight infections and diseases. Unfortunately, these cells can become malignant and turn against us in the form of blood cancer.
Leukemia is a blood cancer caused by the uncontrolled production of abnormal white blood cells in the bone marrow, also known as the ‘blood factory’ of the body. When this happens, the abnormal white blood cells crowd out healthy cells, preventing the normal function of the bone marrow, and then eventually enter the bloodstream.
There are four main types of leukemia, classified by the type of white blood cell affected (myeloid or lymphoid) and rate of disease progression (chronic or acute):
- Chronic myeloid leukemia (CML)
- Chronic lymphocytic leukemia (CLL)
- Acute myeloid leukemia (AML)
- Acute lymphocytic leukemia (ALL)
Chronic leukemia is slower-growing and insidious, while acute leukemia involves the rapid expansion of leukemia cells that progresses quickly without treatment. Each type comes with its own set of unique characteristics, prognosis and treatment modalities.
Symptoms of leukemia
Leukemia symptoms may vary, depending on the type of leukemia. Generally, some common signs and symptoms include:
- Pale skin
- Feeling weak
- Loss of appetite and weight loss
- Night sweats or excessive sweating
- Bleeding gums or nosebleeds
- Easy bruising
- Red or purple spots on the skin
- Bone or joint pain
- Frequent or severe infections
These symptoms are typically related to low red blood cell count or anaemia, and/or low platelet count resulting from cancerous cells crowding out healthy cells in the bone marrow.
How is leukemia managed?
Advances in cancer research and technologies over the years have led to evolutions in treatment for blood cancers, including leukemia. Today, leukemia can be managed by a wide array of treatment modalities, depending on the type of disease.
Targeted therapy is a novel treatment that targets specific genes and proteins that control how cancer cells grow, divide and spread. The treatment is more accurate and directed to the cancer specifically, and thus have less adverse effects on surrounding healthy cells compared to chemotherapy. This means that patients spend less time in the hospital, and can go about their daily lives while on medication without worrying about severe side effects.
Thanks to such medical advances, the treatment paradigm for chronic leukemia has shifted from traditional systemic treatment to targeted therapy alone.
Acute leukemia is usually treated with intensive remission-induction chemotherapy aimed at the cancerous cells in the bone marrow, followed by maintenance of response with post-remission therapy. By getting the disease into remission, the cancerous cells can no longer be detected, and normal healthy blood cells can return to normal levels.
Patients with acute leukemia can expect chemotherapy treatment to be more intense compared to patients with chronic leukemia because of the more aggressive nature of the disease.
Stem Cell Transplant
Chemotherapy alone is sometimes not sufficient to completely eradicate cancer cells, especially for acute leukemia.
Stem Cell Transplant (SCT), also known as bone marrow transplant, is a highly specialised procedure that involves replacing the patient’s immune system and the unhealthy bone marrow with a healthy immune system and normal blood (or bone marrow) stem cells from a donor.
There are two types of SCTs: autologous and allogeneic. Autologous SCT uses bone marrow or peripheral blood stem cells from the patient, while allogeneic SCT uses stem cells from a suitably matched donor.
Because of the rigorous conditioning regimen, risks and intense side effects, patients’ eligibility for SCT need to be assessed based on certain criteria such as age and availability of matching donors.
CAR T-cell Therapy
One of the latest developments in blood cancer treatment is Chimeric Antigen Receptor (CAR) T-cell Therapy, which involves genetically engineering the T-cells from a patient in a laboratory setting and getting them to recognise certain targets on cancer cells. These modified cells, when re-infused into the patient, have the ability to destroy cancer cells using the patient’s own immune response.
While CAR T-cell Therapy is a relatively new development, it has generally shown good overall response rates in different kinds of blood cancers. Currently, CAR T-cell Therapy is only approved for the treatment of relapsed or refractory B-cell Acute Lymphoblastic Lymphoma (ALL) in paediatrics and young adult patients, and relapsed or refractory Diffuse Large B-cell Lymphoma (DLBCL).
When to see a doctor
Like many diseases, symptoms of leukemia may be overlooked because they resemble symptoms of common illnesses. If you notice any persistent signs or symptoms that worry you, do not hesitate to see a doctor.
A key step in the management of leukemia is to find the correct diagnosis and subtype of the disease. To determine this, patients would typically undergo a physical examination, blood test and bone marrow biopsy. Further tests such as genetic testing and imaging tests may also be carried out to determine the extent of the disease.
Such tests not only help to determine the diagnosis, prognosis and extent of the disease, but also helps doctors come up with a personalised treatment plan that is appropriate for the patient’s individual profile and their disease.