Leukemia types and history
Leukemia is a cancer of the bone marrow, where new blood cells are made. As the disease progresses, leukemia cells are usually found in the bone marrow and in the blood.While there are several types of leukemia, they all start with problems in the creation of blood cells.
In a healthy person, immature stem cells in the bone marrow develop through several stages, eventually forming healthy, mature blood cells.
These cell types include:
White blood cells, which are part of the immune system.
There are several types of white blood cells, including granulocytes (most commonly neutrophils) and mononuclear cells (B cells, T cells, NK cells and monocytes).
When a person develops leukemia, one of the stem cells becomes abnormal or cancerous at some point in its development. It then multiplies uncontrollably.
These cancerous cells don’t do their job well and they crowd out healthy cells in the bone marrow and in the bloodstream. This leaves the patient prone to infection, at increased risk for bleeding, weak and sometimes short of breath.
Two main Leukemia types :
Most leukemia cases fall into one of two categories, chronic and acute.
Chronic leukemia involves mature or partially mature cells and is slow growing. Acute leukemia impacts immature cells and is more aggressive. The disease is further broken down by the type of blood stem cell involved: myeloid or lymphoid.
Of the four primary types of leukemia, acute lymphoblastic leukemia (ALL) is the least common. About 6,000 new cases are diagnosed in the United States each year. While people of all ages develop ALL, a majority of new diagnoses are in people under age 20. The five-year survival rate is 68%.
More about Acute Leukemia:
ALL impacts lymphoid stem cells. In healthy bone marrow, lymphoid stem cells, or lymphoblasts, form mature lymphocytes, a type of disease-fighting white blood cell. In ALL, lymphoid stem cells make diseased lymphoblasts, which rapidly grow. They eventually take over the bone marrow and cause high counts in the blood. ALL cells are immature and grow rapidly. They are poor at fighting infection and crowd out healthy cells.
Acute myeloid leukemia (AML) AML affects myeloid stem cells. When healthy, these stem cells make three blood components:
AML occurs when a myeloid stem cell becomes cancerous. In these cases, the myeloid stem cells produce diseased cells. These cells don’t do their job well and multiply so rapidly that they crowd out healthy cells. AML can severely weaken the patient’s immune system, leading to frequent infections.
AML is the most common acute leukemia in adults. While pediatric patients can develop the disease, most diagnoses are in people over age 55. The median age of diagnosis is 68.
As an acute leukemia, AML is aggressive and can be particularly difficult to treat. Its five-year survival rate is less than 28%, though that figure differs based on the exact subtype of each person’s cancer.
Most of these AML subtypes are based on how the diseased cells differ from healthy cells and how far along they are in the development process. Specific chromosome abnormalities in the cancer cells and the disease’s own genetic mutations also impact the prognosis.
Chronic Lymphoblastic Leukemia:
Chronic lymphoblastic leukemia (CLL) is the most common type of adult leukemia. The disease is virtually unheard of in children and it primarily affects older adults. Almost 90% of new cases are in people age 55 and older, while the average age at the time of diagnosis is 72.
CLL develops from B cells. B cells start out as lymphoid stem cells, then mature into adult B cells. In CLL, a cancerous B cell grows and multiplies in the bone marrow, lymph nodes, liver, spleen and results in a high white blood cell count. These cancerous cells are not able to fight infection.
They also crowd out healthy cells from the marrow, and cause enlargement of lymph nodes, liver and spleen.
As a chronic disease, CLL is less aggressive than acute forms of leukemia. It has a five-year survival rate of around 90%. The presence of specific genetic mutations and proteins produced by the diseased cells, however, can have a big impact on the patient’s prognosis.
For CLL patients, clinical studies have not shown a benefit to beginning treatment immediately after diagnosis versus when the disease develops to a set point, known as an indication for treatment. Because of this, doctors often recommend “watchful waiting” for early stage CLL.
Watchful waiting of CLL:
During watchful waiting, patients undergo regular blood tests to monitor the disease’s progress. Specifically, doctors look for an increase in leukemia cell count and decreases in hemoglobin and platelet count. Symptoms are treated as they arise. If and when patients develop an indication for treatment, initial treatments can include targeted therapy and a combined chemotherapy/immunotherapy treatment.
In most cases, these treatments put patients into remission. Some patients may need continued treatment to maintain remission. For others, remission is complete and they may stop treatment.
All CLL patients in remission are at risk of recurrence, requiring that they undergo other treatments. Typically patients go through multiple courses of treatment through the span of their disease.
Chronic Myeloid Leukemia:
Chronic myeloid leukemia (CML) primarily affects adults. About 68% of new cases are in people 55 or older, while the average age of diagnosis is 65.
CML involves myeloid stem cells. When healthy, these cells form neutrophils, a type of mature white blood cell. In CML, the myeloid stem cells become cancerous. The myeloid stem cells may not fully mature and are poor at doing their jobs. They can eventually crowd healthy blood cells out of the bone marrow and cause a high white blood cell count and an enlarged spleen.
As a chronic disease, CML is relatively slow to develop, and its five-year survival rate is nearly 68%. The patient’s exact subtype of CML can impact his or her prognosis and treatment plan.
While most cases of leukemia fall into one of the four subtypes above, there are other, rarer forms of the disease.
Rare forms include :
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive sub-type of acute leukemia that impacts approximately 500 to 1,000 people in the U.S. a year. Though it can affect people of any age, the disease is most common among older patients, with about half of new diagnoses coming in patients age 70 or older. Historically, it has been associated with poor survival rates.
BPDCN is a cancer of a specific type of cell known as plasmacytoid dendritic cells. This rare type of immune system cell is usually found in the skin, bone marrow, blood, lymph nodes and spleen.
As a result, symptoms usually can impact these areas. Skin lesions are the most common BPDCN symptom. These can show up anywhere on the body, but often appear on the arms, legs, face and neck. Other symptoms include low counts of healthy blood cells and swollen lymph nodes.
Traditionally, BPDCN has been treated with chemotherapy, while younger, fitter patients have been given the option of a stem cell transplant. The FDA has recently approved a new targeted therapy drug that attacks CD123, a molecule commonly found on the surface of BPDCN cells. This targeted therapy is now considered a standard treatment for the disease.
In hairy cell leukemia, lymphoid stem cells produce too many diseased B cells. Hairy cell leukemia is typically slow to develop and progress. Because of this, doctors often recommend “watchful waiting” in which they simply monitor the disease instead of immediately ordering treatments like chemotherapy or targeted therapy.
T cell prolymphocytic leukemia is an aggressive form of the disease involving lymphoid stem cells, particularly T cells. It is linked to genetic damage that develops during the patient’s lifetime. This damage is not passed down from parent to child. Because the disease is usually aggressive, doctors typically recommend that treatment begins as soon as possible. To understand what happens to your blood when you have leukemia, it helps to know what makes up normal blood and bone marrow.
What ACH can provide you.
Using a comprehensive team approach, we work together to give you customized care that includes the most advanced diagnostic methods and treatments.
Successful leukemia treatment begins with accurate and precise diagnosis. As many as 15% of leukemia patients have been misdiagnosed before they come to ACH. We have the expertise and experience gained from being one of the most active programs in the world, and our specialized pathologists are highly skilled in diagnosing leukemia.
Our approach to leukemia is customized especially for you. We carefully evaluate your risk factors and the specific characteristics of your leukemia to determine if immediate treatment is necessary. If it is, we recommend the most effective therapies while aiming to limit treatment side effects.
Whether you are treated as an inpatient or outpatient, our comprehensive program offers all the services needed to care for leukemia and its impact on your body. We aim to accomplish as much care as possible on an outpatient basis. If hospitalization is needed, our expert staff is specially trained to handle any complications that may arise.