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. Leukemia is 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 lymphocytic leukemia (CLL) is also called chronic lymphoid leukemia.

CLL starts when changes happen in very early or immature forms of white bloods cells called lymphocytes. These are a type of white blood cell that helps fight infections. People with CLL have too many lymphocytes in their blood. But these cells aren't normal and they don't help fight infection. In fact, people with CLL are more likely to get infections. And because the abnormal lymphocytes fill up the bone marrow, people with CLL can also have low levels of other blood cells, such as red blood cells and platelets. This leads to other problems. Not having enough red blood cells is called anemia. It can cause tiredness (fatigue). Low platelet levels can lead to 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 may not be in your control. But others may be things you can change.

The risk factors for CLL include:

• Being exposed to the chemical Agent Orange during the Vietnam War.
• Having a family history of CLL.
• Being older in age.
• Being male.

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

There's no sure way to prevent CLL.

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

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

Common symptoms of CLL include:

• Feeling very tired or weak.
• Fevers with no clear cause.
• Night sweats.
• Frequent infections.
• Enlarged lymph nodes, often felt as lumps beneath the skin.
• Pain or fullness in the upper left belly (abdomen) from an enlarged spleen.
• Losing weight without trying.
• Bleeding and bruising easily.
• 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.

CLL is often found when blood tests are done for another reason, like part of a routine physical. If your doctor thinks you may have CLL, exams and tests will be needed to be 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 more of these tests:

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

After a diagnosis of CLL, you'll likely need other tests. These help your doctors learn more about your cancer. They can help determine the stage of the cancer. The stage is how much and how far the cancer has spread, or metastasized, in your body. It's one of the most important things to know when deciding how to treat the cancer.

Once your cancer is staged, your doctor will talk with you about what the stage means for your treatment. Be sure to ask your doctor to explain the stage of your cancer to you in a way you can understand.

Your treatment timing and choices depend on a number of factors. These include:

• The kinds of chromosome changes in the CLL cells.
• The speed at which the CLL cells are growing.
• Other test results.
• Your age.
• Your overall health.
• The stage of the cancer.

The goal of treatment may be to control the cancer or help ease problems caused by the cancer. There's no cure for CLL at this time. Talk with your health care team about your treatment choices, the goals of treatment, and what the risks and side effects may be.

Types of treatment for cancer are either local or systemic. Local treatments remove, destroy, or control cancer cells in one area. Surgery and radiation therapy are local treatments that may be used in certain cases of CLL.

Systemic treatments destroy or control cancer cells that have traveled around your body. When taken by pill or injection, chemotherapy, targeted therapy, and immunotherapy are systemic treatments.

CLL tends to grow slowly and often doesn't need to be treated right away. Your health care team may keep track of your condition to see if treatment is needed. This is called watchful waiting. If and when treatment is needed, 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 CLL include:

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

Talk with your doctors 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 hair loss, mouth sores, skin changes, appetite loss, diarrhea, and vomiting.

Talk with your doctor about any 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 effect of cancer and its symptoms on your daily life.

Here are some tips:

• Talk with your family or friends.
• Ask your healthcare 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 your symptoms get worse.
• You have signs of an infection, such as a fever or chills.
• You have side effects of treatment that 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 a new diagnosis and any 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.