Cancer starts when cells change (mutate) and grow out of control. The changed (abnormal) cells often grow to form a lump or mass called a tumor.

Leukemia is different from most other types of cancer. Leukemia cells don't often form tumors. It's a cancer that starts in the bone marrow. The bone marrow is where new blood cells are made. It's the thick, sponge-like tissue in the center of certain bones.

When a person has leukemia, the body makes too many abnormal blood cells. They can crowd out healthy cells in the bone marrow. Not enough of all the different types of blood cells are made. Leukemia cells travel throughout your body in your blood. So leukemia can affect organs all over your body.

Chronic myeloid leukemia (CML) is also called chronic myelocytic and chronic myelogenous leukemia.

CML starts in myeloid stem cells that normally mature into red blood cells, white blood cells, and platelets. An abnormal chromosome is formed in very early or immature forms of the myeloid stem cells in the bone marrow. The chromosome is called the Philadelphia chromosome. It's made up of 2 fused genes that form a gene called BCR::ABL1. This gene turns the normal cell into a CML cell that grows and divides out of control.

People with CML have too many white blood cells in their blood. Over time, the person might not have enough red blood cells. This is called anemia, and it can cause tiredness (fatigue). CML can lead to too few platelets, too. This causes easy bleeding and bruising.

A risk factor is anything that may increase your chance of having a disease. The exact cause of someone's cancer may not be known. But risk factors can make it more likely for a person to have cancer. Some risk factors may not be in your control. Others may be things you can change.

Risk factors for CML include:

• Being accidentally exposed to very high levels of radiation.
• Being older in age.
• Being biologically male.

Talk with your doctor about your risk factors for CML and what you can do about them.

There's no sure way to prevent CML.

There are currently no regular screening tests for CML. Screening tests are done to check for disease in people who don't have symptoms.

CML tends to grow slowly. Many people with CML don't have any symptoms when it's first found.

Common symptoms of CML include:

• Feeling very tired or weak.
• Fevers with no clear cause.
• Night sweats.
• Frequent infections.
• Pain or a sense of fullness in the left upper belly (abdomen) from an enlarged spleen.
• Feeling full after eating only a small amount.
• Losing weight without trying.
• Bleeding and bruising easily.
• Bone or joint pain.
• Itchy skin.
• Shortness of breath.

Many of these may be caused by other more common health problems. But it's important to see a doctor if you have these symptoms. Only a doctor can tell if you have cancer.

CML is often found when blood tests are done for another reason, like during a routine physical. If your doctor thinks you may have CML, exams and tests will be needed to make sure. Your doctor will ask you about your health history, symptoms, risk factors, and family history of disease. A physical exam will be done.

You may also have one or both of these tests:

• Blood tests (many different kinds)
• Bone marrow aspiration and biopsy

After a diagnosis of CML, you'll likely need other tests. These help your doctors learn more about your cancer. They can help determine the phase of the cancer. The phase of CML is based on the number of blast cells in your blood or bone marrow. The tests also show how the CML cells are affecting your other blood cell counts and how fast the cells are growing. All this information helps your health care team figure out the best treatment plan for you.

Your treatment choices depend on test results, your age, your overall health, the speed at which the CML cells are growing, and the phase of the cancer. The goal of treatment may be to cure you, control the cancer, or help ease problems caused by cancer. Talk with your health care team about your treatment choices, the goals of treatment, and what the risks and side effects may be.

Systemic treatment is done to destroy or control cancer cells that may have traveled around your body. When taken by pill or injection, chemotherapy, immunotherapy, and targeted therapy are systemic treatments. People with CML get systemic treatment.

You may have just one treatment or a combination of treatments. Tests will be done during treatment to see how well it's working.

Treatments for CML include:

• Targeted therapy.
• Immunotherapy.
• Chemotherapy.
• Stem cell transplant.

Talk with your doctor about your treatment choices. Make a list of questions. Think about the benefits and possible side effects of each choice. Talk about your concerns with your doctor before making a decision.

Cancer treatment can damage normal cells. This causes side effects like mouth sores, skin changes, appetite loss, and vomiting. Many side effects get better after treatment ends, but some can last the rest of your life.

Talk with your doctor about side effects linked to your treatment. Be sure you know what to watch for. There are often ways to manage and even prevent side effects.

Many people feel worried, depressed, and stressed when dealing with cancer. Getting treatment for cancer can be hard on your mind and body. Keep talking with your health care team about any problems or concerns you have. Work together to ease the effects of cancer and its symptoms on your daily life.

Here are some tips:

• Talk with your family or friends.
• Ask your health care team or social worker for help.
• Speak with a counselor.
• Talk with a spiritual advisor, such as a minister or rabbi.
• Ask your health care team about medicines for depression or anxiety.
• Keep socially active.
• Join a cancer support group in person or online.

Cancer treatment is also hard on the body. To help yourself stay healthier, try to:

• Eat healthy foods, with a focus on high-protein foods.
• Drink plenty of water, fruit juices, and other liquids.
• Keep physically active.
• Rest as much as needed.
• Talk with your health care team about ways to manage treatment side effects.
• Take your medicines as directed by your team.

Your doctor will talk with you about when to call. You may be told to call if:

• You have new symptoms or symptoms that get worse.
• You have signs of an infection, such as a fever or chills.
• The treatment side effects affect your daily function or don't get better with treatment.

Ask your doctor what signs to watch for and when to call. Know how to get help after office hours and on weekends and holidays.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of any new diagnosis and new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose of that visit.
• Know how you can contact your doctor if you have questions.