Leukemia: A cancer that affects children and adults

By Jessica Saenz

The term "leukemia" is broadly used to describe cancer of the body's blood-forming tissues, including bone marrow and the lymphatic system. This type of cancer accounts for approximately 3.2% of new cancer cases in the U.S., according to the National Cancer Institute. Approximately 1.5% of men and women will be diagnosed with leukemia.

If you or someone you love has been diagnosed with leukemia, learning more about the disease can help you cope.

Here's a quick overview to get you started:

There is more than one type of leukemia.

There are many types of leukemia, and they vary by the type of blood cell affected and how rapidly the cells grow and divide. When a blood cell becomes leukemic, it does not perform the functions of a normal blood cell or follow the typical life cycle of a healthy cell.

"We break leukemia down into acute leukemia and chronic leukemia," says James Foran, M.D., chair of the Acute Leukemia and Myeloid Neoplasms Disease Group at Mayo Clinic Cancer Center.

"In acute leukemia, the early bone marrow cells that are growing throughout your life — either myeloid or lymphoid cells — become dysregulated and overgrow in the bone marrow, which spills into the blood," he says. "Chronic leukemia is different. Cells that should be dying begin to accumulate. Chronic types of leukemia usually develop over years, as opposed to acute types of leukemia that develop over months ― sometimes faster."

Regardless of whether leukemia is acute or chronic, it always involves abnormal blood cell counts. "Patients see a disruption in the normal numbers, typically an increase in white cells. They also have nonspecific symptoms at first: fatigue, bruising and sometimes fever if the white blood cell count drops. There are also situations where you could have leukemia with a skin rash or leukemia that forms a lump, but that's an exception," says Dr. Foran.

Experts don't know the cause of leukemia, but they know some of the risk factors.

Leukemia is thought to occur when some blood cells acquire changes or mutations in their DNA that tell the blood cells to continue growing and dividing. When this happens, blood cell production becomes out of control. Over time, these abnormal cells can crowd out healthy blood cells in the bone marrow, leading to fewer healthy white blood cells, red blood cells and platelets, and causing the signs and symptoms of leukemia.

"We don't know what causes leukemia," says Dr. Foran. "But we know there are certain risk factors. We know that someone who smokes is a little more likely to get leukemia, and obesity is also associated with an increased risk."

Certain genetic disorders, such as Down syndrome, are also associated with an increased risk of leukemia, as is exposure to certain chemicals, such as benzene found in gasoline.

Family history might also contribute to chronic leukemia risk.

"For chronic types of leukemia, especially chronic lymphocytic leukemia, we've learned that about 10% ― possibly more ― can run in the family," says Dr. Foran. "In some rare situations, acute leukemia can also run in families."

Dr. Foran says it's difficult to attribute the cause of leukemia to a single factor, with one exception: "If someone's been treated for another cancer and they received radiation treatment or chemotherapy, there's a less than 1% chance that they can develop leukemia due to the stress on the blood," he says.

The most common type of childhood cancer mostly develops in older adults.

Leukemia is often thought of as a childhood cancer. But while acute lymphocytic leukemia most commonly affects children, most cases of leukemia are diagnosed in older adults. "The average age of diagnosis of acute leukemia is around 70 years of age," says Dr. Foran.

"For patients over the age of 60–65, leukemia can be more difficult," says Dr. Foran. "Sometimes people have a comorbid disease like diabetes or heart disease that makes it harder to go through treatment."

Despite such challenges, he says it's better to treat the patient and moderate the side effects of therapies, such as radiation and chemotherapy.

"Even if you can't cure someone, you can help them feel better, live longer and improve their quality of life. The first goal is to get a patient feeling better. The second goal is to see if there is an opportunity to cure that person when the moment is right," he says.

In children with leukemia, the cure rate is quite high. "One of the great successes in the last 40 to 50 years is the treatment of childhood acute leukemia. Through a series of studies, we've learned that we can cure most children — in some cases 80% or higher — with intensive chemotherapy treatments," says Dr. Foran.

New therapies are changing the way leukemia is treated.

Chemotherapy is still the most common form of treatment for acute leukemia, but for chronic leukemia, targeted drug therapy is improving patient outcomes.

"All patients with chronic myelogenous leukemia have an abnormal chromosome that they acquire — they're not born with it — called the Philadelphia chromosome. There are oral medications called tyrosine kinase inhibitors that can target that chromosome to put patients in long-term remission," says Dr. Foran.

Immunotherapy, which uses the immune system to attack cancer cells, also is being explored for the treatment of acute leukemia.

"One of the great innovations in acute leukemia is the use of chimeric antigen receptor-T cell therapy, also known as CAR-T cell therapy. CAR-T cell therapy is an immune treatment in which a person's T cells are genetically modified to target leukemia cells," says Dr. Foran. CAR-T cell therapy has been approved to treat people up to 25 years of age with B cell precursor acute lymphoblastic leukemia. This therapy is being studied for use in people older than 25.

Receiving a leukemia diagnosis can be scary, but treatment advances offer hope. "Leukemia is a shocking word," says Dr. Foran. "My message is: Stop, catch your breath and get the best advice you can."

Educate yourself about the disease, but don't overwhelm yourself with information. Start with your health care provider for answers to your questions and resources for more information and support. Family, friends, support groups and online communities also can help you cope with a leukemia diagnosis.

"We can do something for everyone who has leukemia," says Dr. Foran. "Whether we cure it or not, we can have an impact on it in some positive way."

A version of this story was originally published as a podcast on the Mayo Clinic News Network.

Learn more

Learn more about leukemia and find a leukemia clinical trial. Also, join the Blood Cancers and Disorders Group on Mayo Clinic Connect.