Blood Cancer Overview

Blood cancer, or hematologic cancer, is a big tent encompassing a variety of cancers that affect blood cells, bone marrow, and the lymph system. Leukemia, lymphoma, and myeloma are common blood cancers, accounting for about 10% of all cancers diagnosed in the US each year.

Blood cancer often begins in bone marrow, where blood cells are made. It can also start in the body's lymph nodes. Most blood cancers arise from an overgrowth of abnormal white blood cells.

Signs of blood cancer vary by type. A person may experience fever, fatigue, weight loss, anemia, swollen lymph nodes, or bone pain. Some types produce immediate symptoms, while others progress quietly and slowly over time. Blood cancer can interfere with blood cells' normal blood-clotting and infection-fighting functions. Treatments for blood cancer run the gamut—from active surveillance to chemotherapy, radiation, bone marrow/stem cell transplant, and other cancer therapies.

What Is It?

Most blood cancers are considered liquid tumors, in contrast with breast, lung, and colorectal cancers that typically form lumps, lesions, and polyps. Some blood cancers develop in blood and bone marrow, and others start in the lymph nodes or in other lymphatic tissue.

These are the tissues, cells, and body systems that can be impacted:

Bone marrow: This is the spongy tissue inside your bones that contains blood-forming stem cells. Leukemia and myeloma are types of bone marrow cancer.

Blood cells: Stem cells in your bone marrow form these three types of blood cells:

• Red blood cells that carry oxygen throughout the body.
• White blood cells, the body's infection-fighting cells.
• Platelets, or cell fragments that play a role in blood clotting.

Lymph (or lymphatic) system: This network of tissues, vessels, and organs is a major part of the body's immune system. It carries lymphocytes, a type of white blood cell.

• T lymphocytes (T cells) kill germ and tumor cells.
• B lymphocytes (B cells) make antibodies.

Types

There are three main types of blood cancer plus a slew of subtypes.

Leukemia is cancer of the blood and bone marrow. It can be acute or chronic, depending on how quickly or slowly the cancer grows, and may affect myeloid cells (which can become red blood cells, white blood cells, or platelets) or lymphoid cells (a type of white blood cell). There are four major types of leukemia:

• Acute lymphocytic leukemia.
• Chronic lymphocytic leukemia.
• Acute myeloid leukemia.
• Chronic myeloid leukemia.

Lymphoma is cancer of the lymphatic system. It affects white blood cells known as lymphocytes. There are two main types of lymphoma:

• Hodgkin lymphoma, which usually starts in lymphocytes called B cells.
• Non-Hodgkin lymphoma, a type that begins in B cells or T cells and may be described as indolent or aggressive, depending on how slowly or quickly the cancer is growing and spreading.

Myeloma (aka multiple myeloma) is a cancer that affects plasma cells, a type of white blood cell that produces infection-fighting antibodies. Myeloma is the least common blood cancer.

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Symptoms

Blood cancer symptoms vary by type and subtype. Some blood cancers may have no immediate symptoms.

Common signs and symptoms of blood cancer include:

• Fever.
• Fatigue.
• Unexplained weight loss.
• Easy bleeding or bruising.
• Bone, joint, or abdominal pain.
• Swelling of lymph nodes, liver, or spleen.
• Weakness or numbness.
• Unexplained itchiness or rashes.
• Frequent infections.
• Pale complexion.
• Feeling of fullness.
• Cough or chest pain.

Causes

Blood cancer is thought to be the consequence of certain genetic and environmental changes that permit healthy blood cells to mutate and proliferate. With leukemia, for instance, the growth of abnormal white blood cells impedes normal cell development. While it's not clear why one person develops a blood cancer and someone else does not, there are certain risk factors that can make people more susceptible.

Leukemia risk factors:

• Exposure to cancer-causing chemicals, such as formaldehyde or benzene.
• Smoking.
• Chemotherapy treatment.
• Radiation exposure.
• Myelodysplastic syndrome, a disorder that impairs normal blood cell production.
• Having a first-degree relative with the disease.
• Having Down syndrome

Lymphoma risk factors:

• Older age.
• Having a suppressed immune system due to an autoimmune disease or immunosuppressant treatment.
• Exposure to infections, such as Epstein-Bar, HIV/AIDS, Hepatitis C, and Helicobacter pylori.
• Occupational or environmental exposures to certain chemicals, including pesticides, herbicides, and benzene.
• A genetic predisposition, for example, having a parent, child, or sibling with lymphoma.
• Radiation exposure.
• Being overweight or obese.
• Having textured breast implants.

Diagnosis

Sometimes symptoms launch the diagnostic process; other times abnormalities show up during routine blood work. Your doctor may perform a physical exam to check swelling of your lymph nodes, liver, or spleen, or signs of bleeding or bruising. An X-ray or other imaging tests may be performed.

Blood tests, such as a CBC (complete blood count), can determine levels of white blood cells, red blood cells, and platelets. An elevated white blood cell count may be a sign of leukemia. A bone marrow biopsy may be ordered to look for cancer cells. Blood and tissue samples may be tested to determine the type of leukemia.

Lymphomas are generally diagnosed via biopsy, which involves taking a sample of tissue from an enlarged lymph node to examine under a microscope. Lab and imaging tests can help determine the cancer's location and stage.

A definitive diagnosis of myeloma may require blood and urine testing, imaging, and other tests.

Treatment

Blood cancer treatment depends on many factors. The type of cancer someone has, its location and features, its progression, and a person's overall health are among the variables that are considered. Possible treatment options include:

• Active surveillance/watchful waiting (or monitoring the disease for any changes).
• Chemotherapy.
• Stem cell (bone marrow) transplantation.
• Radiation therapy.
• Targeted therapies.
• Immunotherapy, such as CAR T-cell therapy or monoclonal antibody (rituximab) treatment.
• Surgery (to remove affected lymph nodes or the spleen, for example).
• Blood transfusion.

Participating in a clinical trial may be an option for some blood cancer patients. Palliative care may be given to ease pain and other symptoms.

Prevention

There's no surefire way to prevent blood cancer. The risk of cancer may be out of your control. Most cases of chronic myeloid leukemia, for example, have no known risk factors. Likewise, there are few known risk factors for chronic lymphocytic leukemia. However, your risk of some other types of blood cancer may be reduced by adjusting your lifestyle and avoiding certain environmental factors.

• Avoid unnecessary exposure to radiation.
• Avoid cancer-causing chemicals.
• Don't use tobacco products.
• Avoid risky health behaviors that can increase that chances of AIDS or hepatitis C.
• Stay physically active.
• Eat a healthy diet.

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