Acute Myeloid Leukemia (Adult)
Article updated and reviewed by Corey Cutler, MD MPH FRCP(C), Instructor in Medicine, Harvard Medical School, Dana-Farber Cancer Institute on May 11, 2005.
Acute Myeloid Leukemia is the most common form of myeloid leukemia in adults (chronic lymphocytic leukemia is the most common form of leukemia in adults overall). In contrast, acute myeloid leukemia is an uncommon variant of leukemia in children. The median age at diagnosis of acute myeloid leukemia is 65 years of age, and approximately 9,000 individuals are affected by Acute Myelogenous Leukemia in the United States annually.
There are very few hereditary causes of acute myeloid leukemia. There are very few hereditary causes of acute myeloid leukemia. Certain carcinogens (cancer-causing agents) have been implicated in the etiology of acute myeloid leukemia, including benzene, tobacco smoke, and ionizing radiation. The most important risk factor for acute myeloid leukemia is advancing age. Acute myeloid leukemia can develop in individuals who have received certain types of chemotherapy to treat other cancers. When this occurs, the leukemia is said to be a secondary acute myeloid leukemia. A pre-leukemic disorder termed myelodysplasia, common in older individuals, is also an important risk factor for acute myeloid leukemia.
Most patients seek medical care due to an illness that may include fatigue, fever and recurrent infections, weight loss, night sweats, or bleeding. Patients are often sick only for days to weeks prior to seeking medical attention.
The diagnosis of acute myeloid leukemia is made based on a compatible clinical history and a confirmatory laboratory investigation. A complete blood count (CBC) is almost always abnormal, with leukemic cells often found in the peripheral circulation. Often, the total white blood cell count is elevated, and the red blood cell count is depressed (anemia) as is the platelet count (thrombocytopenia).
A bone marrow examination is almost always required to make the diagnosis of acute myeloid leukemia. The diagnosis of leukemia is confirmed by examination of the cells by microscopy, by the cell surface characteristics of the leukemic cells (based on immunohistochemistry and flow cytometry studies) markers, as well as the presence of certain specific chromosomal abnormalities identified within the leukemic cells.
Leukemia is treated mainly with chemotherapy, although radiotherapy and biological therapy can play a role in certain scenarios. The goals of therapy are to relieve symptoms and put the leukemia into remission and hopefully cure the disease.
Active therapy of leukemia is usually divided into two phases:
1. Induction. This is the attempt to attain an initial remission of the leukemia.
Standard induction therapy for acute myeloid leukemia includes two drugs: An anthracycline (such as daunorubicin or idarubicin) in combination with the nucleoside analogue, cytosine arabinoside. These drugs are administered intravenously over seven days, in the most common induction regimen. Supportive care (including anti-nauseant medications) is required during the initial hospital stay for induction therapy, which often lasts up to one month.
The chemotherapy drugs will kill normal bone marrow and leukemic cells equally, so the most significant side effects besides nausea and vomiting are a temporary reduction of normal white blood cells, red blood cells, and platelets. The lack of white cells results in lowered immunity and a high likelihood of infections. A low platelet count may result in easy bruisability and spontaneous bleeding, and is treated with routine platelet transfusions. A decrease in the red cell count, termed anemia, may result in fatigue, shortness of breath, and lack of energy. Red cell transfusions are therefore used routinely.
2. Consolidation. This involves giving repeated cycles of chemotherapy once the patient appears to be in remission. The purpose of consolidation chemotherapy is to eradicate any microscopic amounts of leukemia that are undetectable using standard diagnostic studies.
Stem cell transplantation is used instead of consolidative chemotherapy in individuals with adverse prognostic features at the time of leukemic diagnosis. Stem cell transplantation is also used in an attempt to cure acute myeloid leukemia that has recurred after standard chemotherapy treatment.
It is also important to consider alternatives to standard therapy for some individuals with acute myeloid leukemia. In the very elderly, the cure rate for acute myeloid leukemia is very low, so consideration of palliative and supportive care is a reasonable option.
Editorial review provided by VeriMed Healthcare Network.