Your blood, which accounts for about 8 percent of your normal body weight, plays an important role in how your body functions. As your blood circulates throughout your vascular system, it supplies all of your organs with oxygen, nutrients, hormones and antibodies. Blood is made of an almost equal mix of plasma (the liquid that transports cells, waste and nutrients, among other things) and blood cells (red blood cells, white blood cells and platelets).

When cancer occurs in the blood, it’s usually the result of an abnormal and excessive reproduction of white blood cells. Blood cancers account for about 10 percent of all diagnosed cancers in the U.S. each year. Blood cancers (including leukemia, lymphoma and myeloma) are more common in men than women. Childhood leukemia accounts for about 25 percent of all cancers in children. 

“Some blood cancers may cause symptoms such as severe fatigue, weight loss, night sweats, or lymph node swelling,” says Scott Frederick Huntington, MD, MPH, a Yale Medicine hematologist in the Department of Hematology. “Other blood cancers may show no symptoms and slowly progress over years.”

Treatments for blood cancers also vary, ranging from active surveillance without cancer-directed therapy to standard cancer treatments including immunotherapies, chemotherapies and targeted agents. “With over 100 different types of blood cancers now recognized, it is important to have an accurate diagnosis prior to deciding on treatment,” says Dr. Huntington. Yale Medicine has both clinicians and pathologists who specialize in blood cancers and review challenging cases during tumor boards to reach a consensus prior to starting therapy. 

Blood has four main parts:

• Plasma, the liquid part of blood that transports nutrients, waste products, and proteins and other molecules responsible for affecting the function of various parts of the body, including regulating body temperature and fluid balance
• Red blood cells, the cells responsible for transporting oxygen to lungs and tissues
• White blood cells, the cells responsible for protecting against infections
• Platelets, the cells that form blood clots and prevent blood loss

Cancer is caused by a dysfunction in cellular growth and behavior. In a healthy body, new white blood cells are regularly generated to replace old, dying ones. The excessive production of white blood cells in the bone marrow leads to blood cancers.   

There are three primary types of blood cancer:

• Leukemia is cancer of white blood cells or cells that become white blood cells. Leukemia prevents white blood cells from fighting infections in your body. Leukemia can be either acute (fast-growing) or chronic (slower-growing), and affect the lymphocytes (lymphocytic leukemia) or other immune cells (myeloid leukemia). It’s the most common blood cancer for children under the age of 15.
• Lymphoma is cancer of the lymphatic system (an important part of the immune system), particularly lymph nodes (small bean-shaped structures of the lymphatic system that filter out harmful substances). It affects a type of white blood cell called lymphocytes. The type doctors know the most about is called Hodgkin’s lymphoma (or Hodgkin’s disease). (All others are called non-Hodgkin lymphoma.) It’s the most common form of blood cancer in adults, accounting for over half of all diagnosed blood cancer cases.
• Myeloma is cancer of the plasma cells, which are lymphocytes that make antibodies to protect against infections. Myeloma affects your body’s immune system, leaving it susceptible to infection.

The risk factors for blood cancer are not fully understood, though it is believed that blood cancers develop from a combination of genetic and environmental factors. Smoking, radiation exposure, and exposure to certain chemicals have all been linked to increased risk of some types of blood cancers. Epstein-Barr virus, HIV and human T-cell lymphoma/leukemia virus infections are also risk factors for developing lymphomas and leukemias.

Symptoms of blood cancer vary by disease but typically include the following:

• Fever
• Chills
• Fatigue
• Weakness
• Bone and joint pain
• Weight loss

The swelling of lymph nodes, liver and spleen are also common, and anemia can occur in some blood cancers.

• Leukemia: Your doctor will obtain a complete blood count (CBC) test, which can identify abnormal levels of white blood cells relative to red blood cells and platelets.
• Lymphoma: Your doctor will need to perform a biopsy, which removes a small portion of tissue to be examined under a microscope. In some cases, your doctor may also order an X-ray, CT or PET scan to detect swollen lymph nodes.
• Myeloma: Your doctor will order a CBC, or other blood or urine tests to detect chemicals or proteins produced as a function of myeloma development. In some cases, bone marrow biopsy, X-ray, MRI, PET, and CT scans can be used to confirm the presence and extent of the spread of myeloma. 

Treatment will depend on several factors. These include the type of blood cancer you have, your age, how fast the cancer is progressing, and whether the cancer has spread to other parts of your body.

Because treatments for blood cancer have vastly improved over the last several decades, many types of blood cancers are now highly treatable. Common treatments include the following:

• Chemotherapy: Anticancer drugs are introduced to the body (via injection into the vein or sometimes by taking a pill) to kill and halt the production of cancer cells.
• Radiation therapy: This form of cancer treatment uses high-energy rays to kill cancer cells.
• Targeted therapies: This form of cancer treatment uses drugs that specifically kill malignant blood cells, without harming normal cells. Targeted therapies are most commonly used to treat leukemia.
• Stem cell transplantation: Healthy stem cells can be infused into your body to help resume healthy blood production following therapy to destroy malignant blood cells.
• Cancer Surgery: This treatment involves removing the affected lymph nodes to treat some lymphomas.
• Immunotherapy: This treatment activates the immune system to specifically kill cancer cells.

Yale uses a multidisciplinary approach to diagnosing and treating blood cancer. “Clinicians specialize within a subgroup of blood cancers (leukemia, lymphoma or myeloma) and meet regularly with pathologists, radiologists and radiation oncologists to ensure consensus on the diagnosis and treatment plan,” says Dr. Huntington. Once the proper diagnosis is made, patients have access to world-class cancer care and cutting edge clinical trials, he says.