Adult Acute Lymphocytic Leukemia:
What Is Adult Acute Lymphocytic Leukemia?

Adult acute lymphocytic leukemia (also called acute lymphoblastic leukemia or ALL) is a disease in which too many infection-fighting white blood cells called lymphocytes develop in the blood and bone marrow.

Lymphocytes are made by the bone marrow and by other organs of the lymph system. Bone marrow is the spongy tissue inside the large bones in the body. Bone marrow cells are produced by immature immortal stem cells. These stem cells produce slightly more mature cells called blasts that develop (mature) into the following types of blood cells that have specific jobs to do in the body:

• Red blood cells carry oxygen and other materials to all tissues of the body.
• White blood cells fight infection.
• Platelets make the blood clot.

Lymphocytes are found in the lymph, a colorless, watery fluid in the lymph vessels. The lymph vessels are part of the lymph system, which is made up of thin tubes that branch, like blood vessels, into all parts of the body.

Along this network of vessels are groups of small, bean-shaped organs called lymph nodes. Clusters of lymph nodes are found in the underarm, pelvis, neck, and abdomen. The spleen (an organ in the upper abdomen that makes lymphocytes and filters old blood cells from the blood), the thymus (a small organ beneath the breastbone), and the tonsils (an organ in the throat) are also part of the lymph system.

Lymphocytes fight infection by making antibodies, which attack germs and other harmful bacteria in the body. In adult acute lymphocytic leukemia, the developing lymphocytes do not mature and they become too numerous. These immature lymphocytes collect in the lymph tissues and make them swell and may crowd out other blood cells in the blood and bone marrow. Because of this crowding, if the bone marrow cannot make enough red blood cells to carry oxygen, then anemia may develop. If the bone marrow cannot make enough platelets to make the blood clot normally, then bleeding or bruising may develop more easily. The cancerous lymphocytes can also invade other organs, the spinal cord, the brain, and the testicles.

Adult acute lymphocytic leukemia progresses quickly and can occur in adults and children. Treatment is different for adults than for children.

Adult Acute Lymphocytic Leukemia:
Treatment Phases

There are two phases of treatment for adult acute lymphocytic leukemia. The first phase is called induction therapy. The purpose of induction therapy is to kill as many of the leukemia cells as possible and make patients go into remission (a condition in which the disease partially or completely disappears). Once in remission with no signs of leukemia, patients enter a second phase of treatment called continuation therapy, which tries to kill any remaining leukemia cells. A patient may receive chemotherapy for up to several years to stay in remission.

The choice of treatment for adult acute lymphocytic leukemia depends on whether the patient has been treated before and the current status of the disease:

Untreated

Untreated adult acute lymphocytic leukemia means that no treatment has been given except to treat symptoms. There are too many white blood cells in the blood and bone marrow, and there may be other signs and symptoms of leukemia. Treatment will probably be systemic chemotherapy. This may be intrathecal chemotherapy alone or combined with either radiation therapy to the brain or high doses of systemic chemotherapy to treat or prevent leukemia in the brain. Treatment may also include blood transfusions, antibiotics, and instructions to keep the body and teeth especially clean. Clinical trials are testing new drugs.

In Remission

Remission means that treatment has been given and that the number of white blood cells and other blood cells in the blood and bone marrow is normal. There are no signs or symptoms of leukemia. Treatment may be one of the following:

·         Clinical trials of short-term, high-dose chemotherapy followed by long-term, low-dose chemotherapy.

·         Clinical trials of allogeneic bone marrow transplantation in which diseased bone marrow is replaced with bone marrow from a donor.

·         Clinical trials of autologous bone marrow transplantation in which a patient’s own diseased bone marrow is removed, treated, and then replaced.

·         Intrathecal chemotherapy into the fluid surrounding the brain, used alone or combined with either radiation to the brain or high doses of systemic chemotherapy, to prevent leukemia cells from growing in the brain (central nervous system or CNS prophylaxis).

Recurrent/Refractory

Recurrent disease means that the leukemia has come back after going into remission. Refractory disease means that the leukemia has failed to go into remission following treatment. Radiation therapy may be given to reduce symptoms. Patients may also choose to take part in a clinical trial of bone marrow transplantation.

Adult Acute Lymphocytic Leukemia:
Treatment Options

The primary treatment for patients with adult acute lymphocytic leukemia is chemotherapy. Radiation therapy may be used in certain cases. Stem cell transplantation is being studied in clinical trials.

If leukemia cells have spread to the brain, patients may receive radiation therapy or chemotherapy to the brain. Patients may also receive central nervous system (CNS) prophylaxis, another type of therapy, to prevent leukemia cells from growing in the brain during induction therapy and remission.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. Some anticancer drugs are injected into a vein (IV) or muscle; others are given by mouth or injected into the skin. Chemotherapy is a systemic treatment, meaning that the drugs flow through the bloodstream to nearly every part of the body to kill cancerous cells. Chemotherapy may sometimes be put into the fluid that surrounds the brain by inserting a needle into the brain or back (intrathecal chemotherapy). It is generally given in cycles: a treatment period is followed by a recovery period, then another treatment period, and so on.

Chemotherapy drugs generally target rapidly dividing cancer cells. However, other cells that also divide rapidly include blood cells, cells that line the digestive tract, and cells in hair follicles. Unfortunately, these healthy cells may also be impacted by the chemotherapy drugs, resulting in side effects such as infections, tiredness, temporary hair loss, mouth sores, and other symptoms.

Not all chemotherapy patients develop all of these symptoms, and they usually go away during the recovery period or after treatment stops. Medicines and other treatments are available to control or minimize many of these symptoms.

Radiation Therapy

Radiation therapy is the use of high-energy x-rays to kill cancer cells and shrink tumors. Radiation for adult acute lymphocytic leukemia usually comes from a machine outside the body (external radiation therapy). The most common side effects of radiation therapy are tiredness, skin reactions in the treated areas (such as a rash or redness), and loss of appetite. Radiation therapy may also cause a decrease in the number of white blood cells that help protect the body against infection. Most of these side effects can be treated or controlled and in most cases they are not permanent.

Stem Cell Transplantation

Stem cell transplantation is a treatment in which a patient’s diseased bone marrow is replaced with healthy stem cells to repopulate the marrow.

Allogeneic Transplant: A transplant using marrow from a relative or person not related to the patient is called an allogeneic transplant.  Allogeneic transplants may be done using either a standard high-dose therapy or a less toxic, nonablative, immunosuppressive therapy.

• In the standard high-dose therapy approach, all of the bone marrow in the body is destroyed with high doses of chemotherapy with or without radiation therapy.  Healthy marrow or blood stem cells are then taken from another person (a donor) whose tissue is the same or almost the same as that of the patient. The donor may be a twin (the best match), a brother or sister, or a person who is not related. The healthy stem cells from the donor are then transferred to the patient through a needle in the vein, and the new marrow replaces the original marrow that was destroyed.
• In a nonmyeloablative transplant, the goal is not to destroy the patient’s marrow but to allow for the donor cells to take hold or “engraft.” In this type of transplant, less intensive medications are used and the marrow is not completely destroyed prior to the transplant.

Autologous Transplant: Another type of bone marrow transplant, called an autologous bone marrow transplant, is being studied in clinical trials. In this type of transplant, blood stem cells are taken from the patient after treatment with drugs to kill cancer cells. The stem cells that were taken from the patient are then frozen and stored.  Next, high-dose chemotherapy is given to the patient with or without radiation therapy to destroy the remaining leukemia cells. The frozen stem cells are then thawed and given back to the patient through a needle in a vein to repopulate the marrow and make blood cells.

A greater chance for recovery occurs in hospitals that do more than five stem cell transplantations a year.

Adult Acute Lymphocytic Leukemia:
Clinical Trials

Another treatment option available to some patients is to participate in a study of a new cancer treatment. Every successful cancer treatment being used today was first tested in a clinical trial, a three-step research process designed to evaluate the safety and effectiveness of new treatments for diseases. Clinical trials are conducted at the end of a much longer process of developing and testing new therapies in the laboratory. Patients who participate in successful trials are the first to benefit from the new therapy.

Doctors in many hospitals and cancer centers across the country conduct clinical trials as new drugs and other therapies become available for treating cancer patients. Each carefully planned study is designed to answer certain questions and to find out specific information about how well a new drug or treatment method works.

All new treatments must go through three steps or phases of clinical trials:

• Phase I trials: These first studies in people evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the muscle), how often, and in what dose. A Phase I trial usually involves only a small number of patients, sometimes as few as a dozen.
• Phase II trials: A Phase II trial continues to test the safety of the drug and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular type of cancer.
• Phase III trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard for treatment. A participant will usually be assigned to the standard treatment group or the new treatment group at random (called randomization). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide.

All clinical trial participants receive the best care possible, and their reactions to the treatment are watched very closely. If the treatment does not seem to be helping, a doctor can take a patient out of a study. A patient may choose to leave a trial at any time. If a patient leaves a research study for any reason, standard care and treatment are still available.