Acute Adult Leukemia
Blood is made of white blood cells, red blood cells, platelets, coagulation factors and proteins. White blood cells fight infection, red blood cells carry oxygen, platelets help blood clotting along with coagulation factors, proteins have variety of functions. Leukemia is cancer of white blood cells. It sometimes involves red blood cells and platelets. Leukemia is lethal because it interferes with such important function of blood. It can develop in any age group from infants to elderly. The disease has different characteristics in each age group. In younger age, it is more curable. In elderly, it is less responsive to treatment and carries higher mortality. Acute leukemia afflicts three to four per hundred thousand population(11,000 new cases per year in US). Children account for one-fourth of the cases. Acute leukemia is the most common malignancy of childhood. Acute lymphoblastic leukemia accounts for 80% of childhood leukemia. Acute myelogenous leukemia accounts for 90% of adult leukemia. The peak incidence is around 3-4 years in children and the median age in adults is 60 years. Some of the etiologic factors are radiation, viruses, chemicals like benzene, chemotherapeutic agents, hereditary conditions like blooms syndrome, Fanconi's anemia and Down's syndrome. In the end stages, myelodysplasia, chronic myelogenous leukemia, myeloproliferative disorders can transform into acute leukemia and become lethal. Acute leukemia are commonly associated with chromosomal abnormalities which are central to the malignant transformation of the white blood cells. These chromosomal defects also have very important prognostic implications. Patients with "bad" chromosomes have poor prognosis and high mortality. Patients with "good" chromosomes are highly responsive to standard treatment and curable in high percentage of cases. Acute myelogenous leukemia is treated with chemotherapy. It is curable in about 40% of patients. The cure rate varies in different subgroups depending upon various prognostic features. The initial treatment is called induction treatment. After successful induction treatment, treatment consists of further high dose chemotherapy, autologous peripheral blood stem cell transplant or allogenic transplant. This choice of treatment depends to a large extent on prognostic features at the time of diagnosis, including very importantly chromosomal abnormalities. Those patients who fail induction treatment or who relapse after above treatment have very poor prognosis and are curable only with allogenic bone marrow transplant.
Acute promyelocytic leukemia has a characteristic chromosomal abnormality and is treated differently. Altrans-retinoic acid(ATRA) is used for induction treatment with very high success rates with minimal toxicity. This has been a major advance in the treatment of leukemia in last decade. Acute lymphoblastic leukemia is curable in up to 80% of children. However, the disease in older age group has adverse prognostic features and hence curable in only up to 30% of patients. The cure rate varies in different subgroups depending upon various prognostic features. Initial therapy is called induction treatment with further chemotherapy called intensification treatment. After these two phases which last a few months, one gets maintenance treatment for nearly two years. Those patients who fail induction treatment or who relapse after above treatment have very poor prognosis and are curable only with allogenic bone marrow transplant.