DISEASES

Chronic Leukemia

INTRODUCTION

There are two main types of chronic leukemia: chronic myeloid leukemia and lymphoid chronic leukemia. Both appear mainly in patients over 50 years  old, and in both of them one can find a great amount of blood cells with normal appearance. Nevertheless, the liklihoods ends there.

CHRONIC LYMPHOID LEUKEMIA

This is the most frequent type of leukemia. It affects mainly people over 60 years old, and is characterized by an increase in the normal aspect lymphocyte count.  It is usually diagnosed “by chance”, because it is detected during laboratory exams looking for other type of illness (pre surgical exams, check–up, etc.). Even if it is an almost asymptomatic disease, in some cases, patients may suffer from weakness, abundant night time sweating,  fever, weight loss, an increase in frequency of infections, among other features. Chronic Lymphoid Leukemia is classified according to certain parameters and the classification has a prognostic value. The evolution of the patients varies; while there are patients in which the disease evolves rapidly, some others may have 10 to 20 years without many problems. Among treatment options for this illness are the use for corticosteroids (usually prednisone), chemotherapy such as fludarabine, chlorambucil, cyclophosphamide, vincristine, and doxorubicine. Some time ago,  according to the patient’s age, an allogeneic bone marrow transplant was not a therapeutic option, since the for the patients  was greater than the probability of cure, or a significant increase in the quality of life and survival time. Since younger patients began to show this illness and today’s method and medication have improved, allogeneic transplant has become safer, and it is nowadays the best option.

CHRONIC MIELOID (GRANULOCITIC) LEUKEMIA

Chronic Myeloid Leukemia (CML) is a blood cancer disease characterized by out of control growth and proliferation of certain white cells (leukocytes) called granulocytes or neutrophils. It was the first cancer almost universally associated with a genetic alteration. Genetic material translocation of two chromosomes occurs (9 and 22), known as the Philadelphia chromosome. This disease occurs usually in patients over 50 or 60 yrs, but infant and juvenile CML also exist. The most common findings at the beginning of the disease are the increment of white cell counts and spleen size. Also, liver size increases, anemia, exhaustion, and bleeding can occur, but  less frequently. In many cases patients are asymptomatic and diagnosis is done by accident, when performing a routine blood test.

CML has many stages. The first one is known as the chronic stage where the patient responds to treatment and its capable of having a normal life, even on strong medication. The second is the accelerated stage, followed by the third stage, known as the blast stage. At this stage, CML can be distinguished from acute leukemia and has a very bad prognosis.

Treatment for CML is based in achieving the chronic stage and holding it for as long as possible, with the help of certain chemotherapeutic agents (hidroxiurea, busulfan and citarabine among others). Followed by  interferon or mixed with some other drugs. Even though great progress have been made in treating this disease, particularly with the use of interferon that has  increased significantly  the time at chronic stage, all treated patients with this drugs will eventually get to the  blast stage. The time it takes between diagnosis and blast stage is unpredictable and it varies enormously among patients, with a 3-4 year average.

Allogeneic transplant is the only potential treatment known that cures this disease. Healing average varies according to the patients characteristics. Young patients transplanted within one year from diagnosis and transplants with an HLA compatible sibling, can reach up to 70% disease-free survival.  When no HLA identical sibling exists in the family, the results achieved using an unrelated HLA identical or almost identical donor are similar to those mentioned above. But when there is no  compatible donor for the patient or he is not in  conditions to receive an allogeneic transplant, the autologous transplant may be used. This is  field where a great deal of research HAS been done. Some treatment modalities include the use of “clean cells” by in vitro or in vivo sampling disease techniques, or providing after transplant substances capable of improving  transplant efficacy. Autologous transplants are performed  nowadays in patients with this type of leukemia and in some of them no data of disease have been detected after several years of follow-up.