Leukaemia

Leukaemia is a cancer of white blood cells, the body's main defence mechanism against infection, It occurs when the developing cells fail to mature properly and multiply abnormally fast; these immature cells accumulate in large numbers in the bone marrow, eventually spilling over into the bloodstream. The most important effect of this groWth of leukaemic cells in the marrow is that production of red cells, normal white cells and platelets is disturbed, and their displacement by the abnormal cells is responsible for the serious effects of the disease. Leukaemia most commonly affects the development of lymphocytes (acute or chronic lymphatic leukaemia) or the granulocyte white cells (acute or chronic granulocytic, or myeloid, leukaemia), but other cells may be affected as well. Apart from excessive exposure to radiation, in almost all cases the cause is unknown.

Leukaemia affects between fifty and sixty people per million each year. Unlike many other forms of cancer it often attacks children and young adults as well as older people. The commonest form of leukaemia in children is the acute lymphatic type. Chronic forms are rare before adulthood, but acute myeloid leukaemia occurs at all ages, with a peak in early adult life. Slightly more women are affected than men.

Symptoms

The main features of the disease are a combination of the symptoms and signs of anaemia (lack of red cells), multiple infections (due to lack of protective white cells) and bleeding (due to lack of platelets). Disorders ranging from boils, small bruises or nosebleeds, to pneumonia or severe internal haemorrhage can all be the first feature of acute leukaemia (myeloid and lymphatic). Weakness, fever, shortness of breath and palpitations are also frequent symptoms.

Patients with chronic myeloid leukaemia complain of weakness and fatigue, and discomfort due to an enlarged spleen. Serious infections and bleeding usually occur when the disease becomes acute. Anaemia and enlargement of the lymph glands and' spleen are usually the initial symptoms in chronic lymphatic leukaemia. The leukaemic lymphocytes affect the production of antibodies and this makes the person prone to infections.

The disease is occasionally found in elderly people who have no symptoms at all, and it may persist for many years and never cause trouble, or change into an acute form.

One of the most remarkable features of the acute forms of leukaemia is the occurrence of what is called remission, when the patient feels well again for a time. This develops either following treatment or may occur spontaneously following an infection such as measles or a blood transfusion.

Treatment

The aim of treatment in acute leukaemia is to induce a remission and to maintain it indefinitely. In acute lymphatic leukaemia of childhood, remission regularly occurs in about ninety per cent of cases and may sometimes be permanent. The remission rate in acute myeloid leukaemia is much lower, about thirty to fifty per cent.

Drugs can suppress the multiplication of leukaemic cells, but also suppress the formation of normal cells by the bone marrow, so that during the early stages of treatment the patient will almost always pass through a dangerous stage which requires blood transfusions to replace the red cells and also platelet transfusions to control bleeding. After this danger period, the condition usually improves dramatically. Treatment may also involve bone marrow transplants and radiotherapy.

True remission does not occur in chronic leukaemia as it does in acute leukaemia. Drugs are used to suppress the cell multiplication and these can control the disease for many years, the patient returning to normal health.