More than 10,000 cases of childhood leukemia are reported annually in India. According to WHO, incidences of blood cancer cases in India are 71,659 in 2012 out of which 53,678 resulted in deaths. India is the 3rd highest blood cancer cases in the world after USA and China. In 2012, leukemia ranked 9 and Non-Hodgkin’s lymphoma ranked 13, among the top 20 cancers in India.
Leukemia is the most common cancer in children but is also often found in older adults. There is a lot of under reporting of blood cancer due to lack of awareness, under-diagnosed and infrastructure. This makes it difficult to estimate the number of blood cancer cases in India. However, based on GLOBOCAN 2012 report from WHO, the survival rate of blood cancer cases is really low. While there is no sufficient data to show that blood cancer incidence is rising in India, the increase in number of bone marrow transplants every year indicates the rising cases of blood cancer.
What is blood cancer?
Blood cancer occurs when blood cells divide and grow abnormally in the bone marrow. There are mainly three types of blood cells. They are Red blood cells, which circulates oxygen to the body, White blood cells, which form our immune system and fight infections and Blood Platelets, which clot blood in case of physical injury. All these cells originate from stem cells produced in bone marrow.
When the DNA of these cells is damaged, large number of cells is produced. The cells do not develop fully and divide rapidly. These immature cells clog the blood or bone marrow and interfere with the functioning of healthy cells. Eventually, this interferes with transportation of oxygen and fighting infections.
There are three main categories of blood cancer based on the types of cells affected. There are many other types of cancers in each category.
Leukemia – Leukemia is when White blood cells do not mature properly and divide rapidly. This compromises the immune system of the body.
There are four common types of Leukemia:
Acute lymphocytic/lymphoblastic leukemia (ALL):
This is most common in children aged below 15 years of age. The type of white blood cells called Lymphocytes is affected by it. Immature lymphocytes are called Lymphoblasts. Lymphoblasts do not mature into lymphocytes and divide rapidly. In acute condition, these cells grow rapidly and interfere with the functioning of immune system. The treatment has to be given immediately.
Acute myeloid/myelogenous leukemia (AML):
It occurs in both adults and children. This involves rapid growth of immature myeloid cells. Myeloid cells mature to for Red blood cells, platelets or neutrophils (type of WBCs). The effected myeloid cells do not mature and clog up blood interfering in oxygen transport and blood clotting. It should be treated immediately.
Chronic Lymphocytic Leukemia (CLL):
Immature lymphocytes, called Lymphoblasts, do not mature into lymphocytes and divide rapidly. They eventually block bone marrow and interfere with the blood functioning. This process is much slower than ALL and hence, be treated gradually.
Chronic myeloid leukemia (CML):
It mainly occurs in adults. This involves production of granulocytes, a special type of myeloid cell, which blocks the bone marrow and decreases the number of healthy cells in the blood. It does not grow as rapid as AML and hence does not need emergency treatment as such.
Lymphoma – Lymphocytes grow rapidly and affect the lymphatic system which is responsible for transportation of white blood cells across the body. All types of lymphoma are staged to determine how far they spread in the body. This helps in administering an effective treatment.
There are two common types of Lymphoma:
Hodgkin’s lymphoma develops from rapid growth of B cells, a type of lymphocytes. It is diagnosed by the presence of distinct large cells called Reed-Sternberg Cells. This is more common than Non-Hodgkin lymphoma.
This develops from rapid growth of T cells, a type of lymphocytes. However, Reed-Sternberg cells are absent in this type.
Myeloma – Cancer affects a type of white blood cells called Plasma cells, which produces antibodies to fight against infections. B lymphocytes which are supposed to mature into Plasma cells do not mature but grow rapidly and block the bone marrow, preventing it from producing other cells. It also breaks down chemical leading to thinning of bones which eventually leads to fractures and pain. This can happen anywhere in the body where bone marrow is present. Myeloma is grouped into stages to provide effective treatment.