What is leukemia and why it happens; warning signs to watch out for

Leukemia is a cancer that gives rise to uncontrolled, abnormal blood cells in the body. It generally involves white blood cells that do not function properly due to their excessive production by bone marrow. Based on how rapidly its cells divide, leukemia can be classified as acute leukemia and chronic myeloid leukaemia. Acute leukemia is considered an aggressive form and can quickly turn fatal. (Also read: World Blood Cancer Day 2022: Oncologist busts common myths about blood cancer)

WHAT IS LEUKEMIA?

Leukemia is a group of disorder giving rise to uncontrolled, abnormal blood cells in the body. It occurs as a result of malignant transformation of pluripotent (i.e., can give rise to both myeloid and lymphoid precursors) hematopoietic stem cells.

WHY LEUKEMIA HAPPENS

Body cells are programmed to grow at a set rate and to die at a set time and whenever there is disruption in this process, either the cells are over produced or the cells don’t die as per the programme which leads to leukaemia or cancer.

"DNA the genetic backbone is the structure which programmes this whole process when cells acquire changes (mutations) in their genetic material or DNA blood cell production becomes out of control. Leading to collection of abnormal cells leading to fewer healthy white blood cells, red blood cells and platelets, causing the signs and symptoms of leukaemia," says Dr. Sunny Jain HOD and Sr. Consultant Medical Oncology Marengo QRG Hospital, Faridabad.

SIGNS AND SYMPTOMS OF LEUKEMIA

· Fever or chills

· Fatigue, weakness

· Frequent or severe infections as the number of normal functioning white cells is low

· Unexplained weight loss

· Organomegaly or abnormal enlargement of spleen and liver

· Easy bleeding as the number of platelets might decrease

· Bone pain or tenderness

TYPES OF LEUKEMIA

Leukemia is usually classified based on the cell of origin and its rapidity to divide, they can be categorized as acute or chronic, and myeloid or lymphoid based on the originator cell.

"Acute leukaemia cells divide rapidly as compared to the chronic leukaemia cells and based on the cell line they are divided as myeloid or lymphoid like Acute myeloid leukaemia (AML) and chronic myeloid leukaemia (CML), involving the myeloid chain; and acute lymphoblastic leukaemia (ALL), and chronic lymphocytic leukaemia (CLL) involving the lymphoid chain. Other less common variants such as mature B-cell and T-cell leukaemia, NK cell-related leukaemia," says Dr. Jain.

WHAT ARE THE CAUSES OF LEUKEMIA

There are multiple genetic and environmental risk factors like-

· Exposure to ionizing radiation

· Previous exposure to chemotherapy

· Viral infections (e.g., human T-cell leukaemia virus, Epstein Barr virus)

· Several genetic syndromes (e.g., Down syndrome, Fanconi anaemia, Bloom syndrome, Li-Fraumeni syndrome)

WHAT IS THE CAUSE OF CHILDHOOD LEUKEMIA

Childhood leukemia is one of the most common types of cancer in children and teen and a child suffering from leukemia may frequently fall ill as leukemia cells could crowd out healthy cells.

"The exact etiology of leukaemia is not very clear. However, the genetic diseases like - Klinefelter and Down syndromes, ataxia telangiectasia, Bloom syndrome, and telomereopathies like Fanconi anemia, dyskeratosis congenita, and Shwachman-Diamond syndrome; germline mutations in RUNX1, CEBPA, etc. increases the chances of childhood leukaemia," says Dr Jain.

Contrary to popular perception, most childhood leukaemia are not inherited. Mutations causing changes in DNA causing leukaemia have been found to be non-inherited either during early ages of life or may be before birth.

HOW TO DIAGNOSE LEUKEMIA?

Dr Jain says a complete blood count (CBC) with peripheral smear provides a very useful information pertaining to the number of red blood cells, different types of white blood cells, and platelets, their shape, sizes, abnormal cells and characteristic cells of leukaemia at times. Any abnormality detected calls for a further detailed investigation like:

· Bone marrow aspiration or biopsy.

· Flow cytometry and immunohistochemistry.

· Other investigations include- USG abdomen, CECT, Lumbar puncture and other investigations.

TREATMENT OPTIONS IN LEUKEMIA

· Chemotherapy consisting of anti-cancer medicines targeting the rapidly dividing cells.

· High-dose chemotherapy with a stem cell transplant- In this treatment stem cells (these are undivided cells which will divide further to give rise to myeloid or leukemoid cell lines) are harvested from the patient’s blood and are stored separately following which we transfuse chemotherapeutic agent - high dose alkylating agents that will kill body cells (normal and abnormal) and then we re-transfer the stem cells in the patient’s body and wait for it to repopulate there by giving rise to normal cell lines.

· Targeted therapy- these are special drugs which target a particular cell type based on the biopsy report and IHC/Flow cytometry.

· Radiation therapy- this is a technique which uses ionizing radiation

· Supportive care- like blood transfusions, platelet infusion, antibiotic and antifungal and other measures as require.

· Clinical trials.

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