Leukaemia Blood cancer and the disorder it causes By Jessie Kok The word “leukaemia” often strikes an ominous chord of fear among those who hear about it. While most Singaporeans will understand it briefly as cancer of the blood and think of it to be often terminal, the disease is actually a form of cancer that affects the body’s blood-making system, including the lymphatic system and bone marrow, and comes in two forms: either acute (coming on suddenly) or chronic (lasting a long time). Due to their nature, these two separate forms of leukaemia adopt different characteristics. Chronic leukaemia rarely affects children, whereas acute leukaemia affects both adults and children. What are the two forms? ACUTE LEUKAEMIA – This takes place when immature blood cells reproduce quickly in the bone marrow and eventually crowd out the healthy cells. When overcrowded or produced in high quantities, these immature, abnormal cells sometimes can spread to other organs and cause damage. This category is further broken down into two separate categories and affect children and teenagers of different age groups: • ACUTE LYMPHOID LEUKAEMIA – This is the most common type of leukaemia that affects children, mainly those younger than 10. It occurs when primitive blood-forming cells called lymphoblasts reproduce without developing into normal blood cells and crowd out healthy blood cells. They can collect in the lymph nodes and cause swelling. Adults sometimes develop acute lymphoid leukaemia, but it is rare in people older than 50. • ACUTE MYELOID LEUKAEMIA – While acute lymphoid leukaemia sees abnormal cells gathering in the lymph nodes, acute myeloid leukaemia sees abnormal cells called myeloblasts crowding in the bone marrow. They interfere with the production of healthy, normal cells that lead to anaemia from the lack of red blood cells, bleeding and bruising (due to the lack of blood platelets and frequent infections since there is lack of healthy white blood cells for protection). About 50% of those diagnosed with this conditions are teenagers and people in their 20s. It is the most common form of acute leukaemia among adults. • CHRONIC LEUKAEMIA – Chronic leukaemia takes place when the body produces too many blood cells that are partly developed but still cannot function like mature blood cells. It usually develops more slowly and is a less dramatic illness than acute leukemia. There are two main types of chronic leukaemia: • CHRONIC LYMPHOID LEUKAEMIA – In this form of leukaemia, the abnormal cells in the bone marrow are a type of blood cell called lymphocytes. These abnormal cells cannot fight infection as well as normal cells can. With chronic lymphoid leukaemia, cancerous cells live in the bone marrow, blood, spleen and lymph nodes, where they cause swelling that appears as swollen glands. It is more likely to develop with age, especially between the ages of 60 to 70. • CHRONIC MYELOID LEUKAEMIA – This form of leukaemia is caused by abnormal cells called myeloid cells that usually involve an abnormality in the genetic code called the Philadelphia chromosome. However, this disease is not an inherited defect. Chronic myeloid leukaemia sometimes can be cured with a bone marrow transplant and occurs most often in people between the ages of 25 and 60. Is it inherited? How does one contract the disease? Due to the variations that leukaemia takes form in, the hereditary issue is not universal. The vast majority of leukaemia occur in people without any family history of leukaemia and are not believed to be inherited. However, some forms of the disease, especially chronic lymphoid leukaemia, occasionally strike close relatives in the same family. Certain genetic abnormalities like Down Syndrome have also been linked to the development of specific forms of leukaemia. In cases of myeloid leukaemia, an increased risk of the illness has been linked to excessive exposure to radiation and to heavy exposure to benzene, a chemical found in unleaded gasoline. Symptoms of leukaemia The early symptoms of leukaemia are like those of common illnesses like flu and include ailments like fever, fatigue, aches in bones and joints, headaches, skin rashes, swollen glands, frequent infections, unexplained weight loss, bleeding or swelling of gums, enlarged spleen or liver or the feeling of abdominal fullness and slow-healing cuts or nosebleeds. A proper diagnosis has to be conducted by a doctor who may not suspect leukaemia based on these symptoms alone. Routine blood tests showing abnormal results or a bone biopsy are usually conducted to get detailed diagnosis and suitable treatments are prescribed. Treatments and prevention New drugs in the market that doctors would prescribe in conjunction with other therapy like radiation, chemotherapy or a bone marrow transplant, comes with its own set of risks (see box). As chronic leukaemia progresses more slowly than acute leukaemia, people with chronic myeloid leukaemia typically have several years of stability before developing a picture more like acute myeloid leukaemia. There is no way to prevent most forms of leukaemia although genetic testing may play a larger role in identifying people who are more likely to develop the illness in the future. Until then, close relatives of people with leukaemia should undergo routine physical exams, unless suspicious symptoms develop. Also, complications may occur when cells from a donor might not match the patient cells well enough. In those cases, the new cells may attack the old, resulting in a condition called graft versus host disease. It may be a double-edged sword that can either cause further problems, or help to cure the cancer because the new cells will also attack any cancer cells that are left.