What is Leukemia?
Leukemia! It is a diagnosis that will turn a parent's heart to ice. Fear is the only thing that floods into the brain. But there are many different types of leukemia, and it is not an inevitable death sentence any more.
Leukemia can best be described as a cancer of the white blood cells. Blood contains two main types of cells - red cells that carry oxygen, and white cells that fight infection and carry out many other functions to control the body. There are many different types of white blood cells, and so there are many types of leukemia.
White blood cells are formed as identical cells in the bone marrow, and then gradually change into many specialized different types of white blood cell. The primitive forms of white blood cell in the marrow are frequently involved in leukemia. At the simplest level, white blood cells are divided into two groups called lymphocytes and myelocytes. Cancer in these can cause lymphatic (or lymphocytic) leukemia and myeloid leukemia.
There are two other large divisions in leukemia: the rapidly developing forms (acute leukemias) and the slowly developing forms (chronic leukemias).
Combining the two types of white cells that can be involved, and the two rates of onset, we come up with four possible combinations: acute lymphatic, acute myeloid, chronic lymphatic and chronic myeloid leukemia.
Acute Lymphatic Leukemia
Acute lymphatic leukemia is the main leukemia of childhood, and its usual age of onset is between three and seven years, but about 20% of cases occur in adults.
The symptoms include tiredness, recurrent infections, bruising, nose bleeds and bleeding from the gums. Every child in the country will have at least one of these symptoms at one time or another, so parents should not start worrying until several of them occur at one time. Only 33 in every one million children will develop leukemia. These children develop progressively more severe infections, including skin infections, abscesses and pneumonia. Bleeding into joints may cause arthritic pains. The liver, spleen and lymph glands in the neck, armpit and groin may be enlarged. The diagnosis can be confirmed by blood tests and taking a sample of the bone marrow. Many patients are diagnosed after a routine blood test for vague symptoms. In other cases, the child may become rapidly very ill with multiple serious infections.
The aim of treatment in this type of leukemia is to cure the patient permanently. The treatment will continue intermittently or continuously for some years, and a wide range of drugs are used, including cytotoxics and immuno-suppressants. There are significant side effects from most of these drugs, and constant monitoring and testing of the patient is required. Other treatments that may be used include blood transfusions, radiotherapy, spinal injections and bone marrow transplants. The choice of treatment will depend upon the individual patient's reactions to treatments, the results of the investigations, and the preference of the treating doctor.
Acute lymphoblastic leukemia can now be cured in 60% of children, and 95% achieve some remission of the disease. Adults with this form of leukemia have slightly poorer results.
Acute Myeloid Leukemia
Acute myeloid leukemia has the same symptoms as the acute lymphoblastic form. It is normally a disease of the elderly but may also occur in children and young adults.
The only way to differentiate the different types of leukemia is by the results obtained from blood tests and bone marrow examination. The marrow sample is usually taken from the breast bone or the pelvic bone. Under a local anesthetic, a needle with a large diameter is bored through the bone and into the marrow. A small amount of marrow is then sucked out. The local anesthetic can give relief from most of the pain, but the marrow itself is quite sensitive.
The treatment of acute myeloid leukemia is also similar to that of acute lymphatic leukemia, although different drugs may be used. Blood transfusions and more intensive radiotherapy are commonly required. Of adults with this form of leukemia, 70% can be given remission from the disease, but fewer than 30% can be cured. If bone marrow transplantation is possible in younger patients, the cure rate rises to 50%.
Chronic Lymphatic Leukemia
Chronic lymphatic leukemia is a slowly progressive form of leukemia that is found almost entirely in the elderly. Most patients have only vague symptoms of tiredness or enlarged glands, and the diagnosis is frequently made after a routine blood test for another reason. The liver and spleen may be enlarged, and in severe cases bleeding from nose and gums and into the skin may occur. Most cases progress very slowly over many years, but about 10% progress at a faster rate. Because of its relatively slow progress in elderly patients, many sufferers are given no treatment at all for chronic lymphatic leukemia. If the disease becomes more active, steroid and cytotoxic drugs are given. Severe anemia or excessive bleeding may require an operation to remove the spleen.
The disease is slowly but relentlessly progressive, with an average survival time of eight years. No cure is possible, but the progression of the disease in its advanced stages may be slowed by medication. Because the patients are elderly, they frequently succumb to other diseases before the leukemia.
Chronic Myeloid Leukemia
Chronic myeloid leukemia is a disorder of middle-aged to elderly people. Patients complain of an intermittent fever, tiredness, excessive sweating, and fullness in the abdomen. The disease is often discovered incidentally on a blood test. The diagnosis is confirmed when a blood test shows a very large number of abnormal white cells present in the blood. The spleen may also be enlarged. Further tests may be performed on the bone marrow to estimate the severity of the leukemia.
There is no great urgency in treatment of this disease until the blood test results reach certain levels. At that point, cytotoxic or immunosuppressive drugs are given to reduce the number of abnormal white blood cells. Many different combinations of drugs are used by different doctors in different hospitals. The medication does not cure the disease, but slows its progress and makes the patient feel better. Unfortunately some of the drugs can have rather unpleasant side effects in some patients. On drug therapy alone, the average survival time is four years.
The other available form of treatment is bone marrow transplantation. Finding a compatible donor is difficult, but if a donor can be found and marrow can be transplanted, 60% of patients with chronic myeloid leukemia can be cured.