Leukemia is a cancer of the blood. More than 50,000 new cases of leukemia are diagnosed each year and it accounts for around one-third of all the cancers that affect children. A leukemia diagnosis can be devastating, but advancements in leukemia treatments have caused death rates to drop over the last several decades. With appropriate treatment, leukemia patients can live for many years after their diagnosis.
Leukemia begins in the bone marrow; the soft tissue in bones that produces blood cells. There are three different types of blood cells:
- Red blood cells that transport oxygen through the body
- Platelets that form blood clots and stop or slow bleeding
- White blood cells that fight disease and infection
When an individual has leukemia, their bone marrow begins producing abnormal white blood cells. While most white blood cells only last for a few days before they’re broken down and reabsorbed, leukemic blood cells continue to multiply even after they become old or damaged. Eventually, if enough of them build up inside the body, they crowd out or suppress the production of normal blood cells.
Types of Leukemia
Doctors categorize leukemia according to how quickly it spreads. Acute leukemia develops from white blood cells that fail to mature. They divide rapidly, build up quickly in the blood stream, and require immediate treatment. Chronic leukemia develops from partially mature white blood cells. They build up slowly and it may take several years before symptoms develop. Doctors divide acute and chronic leukemia even further based on the type of cells they develop from.
Acute Lymphocytic Leukemia
Acute lymphocytic leukemia develops from an early form of white blood cells called lymphocytes. They grow quickly and require immediate medical attention. Acute lymphocytic leukemia is most common in children under 15, but can occur in adults as well. The survival rate for children and adults is high. Ninety percent of children and 69 percent of adults go into remission and stay in remission for five years after their diagnosis, after which it is unlikely their leukemia will recur.
Chronic Lymphocytic Leukemia
Chronic lymphocytic leukemia develops slowly and patients may not experience any initial symptoms and sometimes do not even require treatment. Chronic lymphocytic leukemia is most common in people over 50. The survival rate for chronic lymphocytic leukemia is high. Over 82 percent of patients are still alive five years after their diagnosis.
Acute Myeloid Leukemia
Acute myeloid leukemia is a rapidly developing white cell disorder involving myeloid cells, which includes white cells called granulocytes, platelets, and red blood cells. It’s very aggressive and requires immediate treatment. The survival rate varies, depending on the age of the patient. Though it is most common in adults over 65, they have the lowest survival rate – only 26 percent – while the five-year survival rate for patients under 60 is 70-80 percent.
Chronic Myeloid Leukemia
Chronic myeloid leukemia also begins in myeloid cells, but develops gradually. It’s most common in adults over 60. Thanks to the development of targeted medications, such as imatinib, survival rates for chronic myeloid leukemia have risen steadily over the past 20 years, from 31 percent in the early 1990s to over 60 percent today.
These forms of leukemia account for the majority of cases, but there are rare forms patients should be aware of as well.
- Hairy Cell Leukemia: A slow-growing cancer caused by the overproduction of abnormal B-cells that look hairy when viewed under a microscope.
- Myeloproliferative Disorders: Caused by the production of abnormal white cells, as well as the overproduction of normal blood cells and platelets. Roughly a third of myeloproliferative disorders transform into acute myeloid leukemia.
- Myelodysplastic Syndrome: Also known as bone marrow failure disorder, is caused when the body produces blood cells that are either abnormal or die too quickly.
The causes of leukemia are unknown, but physicians have identified several risk factors: exposure to radiation, exposure to benzene (a chemical used to manufacture plastic, pesticides, and other industrial products), and smoking. People with Down syndrome and Li-Fraumeni syndrome are also more likely to develop the disease, as are people with a family history of the disease.
Leukemia causes a wide range of symptoms, many due to a lack of healthy blood cells. Patients who experience any of the following should consult their doctor.
A build up of leukemia cells in the liver or spleen can enlarge them and cause noticeable swelling on the left side of the abdomen. It may also cause patients to feel “full” and lose their appetite, which often leads to weight loss.
Enlarged Lymph Nodes
When leukemia spreads to lymph nodes near the surface of the skin, it creates visible lumps. They can also create lumps in the chest and abdomen, though these are normally not as visible and can only be detected with a CT or MRI scan.
Anemia is a condition caused by a shortage of red blood cells. Its primary symptoms are fatigue, weakness, dizziness, lightheadedness, and shortness of breath. Patients may also appear pallid and pale.
Joint Pain & Bone Pain
When leukemic cells build up in the bone marrow, it can cause overcrowding and pain in the bones and joints.
Easy Bruising & Persistent Bleeding
Platelets normally clump together around damaged blood vessels and stop the loss of blood. As leukemia causes platelet levels drop, it becomes easier for patients to bruise themselves and takes longer for cuts to stop bleeding.
Because leukemia produces abnormal white blood cells, it weakens the body’s natural immune system and makes it vulnerable to infections. These infections may not be serious, but recur frequently in leukemia patients. Fevers and chills are common side effects.
Swollen or Bleeding Gums
Gum disease is often one of the first visible signs of leukemia. It causes gums to become swollen and bloody. Doctors suspect the problem is related to lower platelet levels.
Patients displaying these symptoms will require a blood and bone marrow test before beginning treatment, to confirm whether they have the disease. During the blood test, a sample of the patient’s blood will be examined under a microscope, to see if it has the normal ratio of red blood cells, platelets, and white blood cells. Doctors will also examine the size and shape of the blood cells, to see if they have their normal shape and structure. If the results of the test are unusual, then doctors perform a bone marrow test. The doctor will extract a small sample of bone marrow using a needle and local anesthetic. If the sample contains an unusually high parentage of white blood cells, treatment will begin.
When formulating a treatment plan with their patient, physicians not only need to consider the type of leukemia the patient has, but also their age, white blood cell count, and overall health.
Chemotherapy for Acute Leukemia
Chemotherapy is the primary treatment for acute leukemia. It’s split into three stages: induction, consolidation, and maintenance. During induction, doctors administer large doses of chemotherapy drugs in order to kill leukemic blood cells and bone marrow and drive the patient into remission as quickly as possible. To safeguard their health, patients receive transfusions of red blood cells and platelets, as well as injections of antibiotics and blood cell growth factors.
Once the patient has entered remission, they begin consolidation therapy – another round of chemotherapy designed to kill lingering leukemic cells and prevent a relapse. Once consolidation has ended, patients continue receiving chemotherapy periodically over the next several years, to prevent a recurrence; this is known as maintenance therapy. The interval between chemotherapy cycles is much greater during this stage and doses of chemotherapy drugs are much lower.
Chemotherapy for Chronic Leukemia
Chemotherapy is also the primary treatment for chronic lymphocytic leukemia. It used to be the primary treatment for chronic myeloid leukemia as well, but since the development of targeted therapies, physicians have been moving away from it. Physicians administer chemotherapy in cycles that last for 3-4 weeks, with a short interval in between for patients to rest and recover. Chemotherapy for chronic leukemia is a combination of intravenous drugs and oral medication, which patients take for 1 or 2 weeks during each cycle.
Targeted therapies kill cancer cells by exploiting weaknesses in their DNA. The number of targeted medications for all types of leukemia has increased dramatically in recent years, enough that targeted therapy is now the primary treatment for chronic myeloid leukemia.
Stem Cell Transplant
Stem cell transplants are given to leukemia patients who require aggressive chemotherapy or radiation. These treatments can severely damage bone marrow, but stem cell injections help restore the damaged tissue and speed recovery. There are two types of stem cell transplants: autologous and allogeneic.
During an autologous transplant, doctors collect stem cells from the patient’s bone marrow and re-inject them after treatment. However, if it’s impossible for doctors to collect stem cells without also collecting leukemic cells, they may perform an allogeneic transplant instead. During this procedure, doctors collect stem cells from a donor, preferably a close relative, to avoid complications, and inject them instead. Stem cell transplants carry a certain degree of risk and may not be suitable for every patient.
Physicians use radiation as an adjunctive therapy for leukemia. It is used to shrink swollen organs such as the liver, spleen, or lymph nodes. It’s also used to kill leukemia cells that have built up in bone marrow, which can cause pain and discomfort; and it’s used to eliminate cancerous tissue before a stem cell transplant.
Surgery cannot be used to treat leukemia directly because leukemic cells spread too quickly throughout the body. However, surgery is used to remove lymph nodes, which allow doctors to stage the cancer. If the cancer causes the spleen to become enlarged, surgeons may remove it using a splenectomy. This only occurs if the enlarged spleen doesn’t respond to chemotherapy or radiation.
Patients who are interested in exploring the latest advances in leukemia should consider volunteering for a clinical trial. Clinical trials are where physicians test new cancer treatments, to see whether they’re more effective than current treatments.