Leukaemia is the most common type of childhood cancer accounting for about 30% of all cancers in this age group. Leukaemia starts when bone marrow stem cells start to produce abnormal white blood cells. Leukaemia is divided into two groups – acute and chronic – and is classified according to the type of abnormal cell found most in the blood: lymphoid cells or myeloid cells. When leukaemia affects lymphoid cells, it is called lymphocytic leukaemia. When myeloid cells are affected, the disease is called myeloid or myelogenous leukaemia.
Acute leukaemias can appear and progress suddenly and require urgent treatment.
Chronic leukaemias usually take much longer to form (over months and sometimes years) and can be monitored so that when treatment is given it is of the most appropriate type.
80% of children with leukaemia will have acute lymphoblastic leukaemia (ALL), which is also known as acute lymphocytic leukaemia. Most of the remainder will have acute myeloid/acute non-lymphocytic (AML/ANLL) leukaemia. Chronic myeloid leukaemia (CML) and other myeloproliferative disorders are rare.
Signs and Symptoms
When bone marrow and other organs are affected by leukaemia blast cells then clinical signs and symptoms present themselves. The most common signs and symptoms are
- Malaise and pallor – due to suppressed or dysfunctional red blood cells
- Infections – due to suppressed or dysfunctional white blood cells
- Abnormal bruising and red spots (petechiae) under the skin – due to reduced blood platelets
- Simultaneous enlargement of both the liver (hepatomegaly) and the spleen (splenomegaly) due to presence of excessive white blood cells
- Lymphadenopathy – swelling of one or more lymph nodes due to presence of excessive white blood cells
- Bone pain – may occur if the cancer has spread to this area due to presence of excessive immature blood cells.
Blood and bone marrow tests are essential for accurate diagnosis and to obtain immunological and cytogenetic markers which give useful prognostic information. Once the diagnosis of leukemia is confirmed more tests are done to look for its involvement of other parts of the body particularly meninges ( covering of brain and spinal cord), which is sometimes involved in leukemia.. Lumber puncture is done to find leukemia cells in cerebrospinal fluid (CFS).
The mainstay of treatment for leukaemia is chemotherapy, sometimes with the addition of radiation therapy. The total duration of treatment for Acute Lymphoblastic Leukemia is about two years for girls and 3 years for boys. First six months of treatment is intensive while rest is relatively easy and mostly as out-patient. For Acute Myeloid Leukemia total duration of treatment is about 6 months with intensive chemotherapy.
Bone marrow transplantation is used for some children who have relapsed or are of high risk of relapse in first remission like in some Acute Myeloid Leukemia. Tissue damaged by the treatment is rebuilt by introducing healthy bone marrow.
Prognosis in acute lymphoblastic leukaemia (ALL) is related to age, white cell count at diagnosis, presence or absence of specific genetic markers and speed of response to initial treatment. 6 out of 10 children diagnosed with ALL will be cured in Pakistan. The prognosis of AML is poor. 4 out of 10 children diagnosed with AML will be cured in Pakistan.